Whirlpool Corp. v. Camco Inc., 2000 SCC 67, [2000] 2 SCR 1067

Whirlpool Corp. v. Camco Inc., [2000] 2 S.C.R. 1067

Camco Inc. and General Electric Company                                     Appellants

v.

Whirlpool Corporation and Inglis Limited                                        Respondents

Indexed as:  Whirlpool Corp. v. Camco Inc.

Neutral citation:  2000 SCC 67.

File No.:  27208.

1999:  December 14; 2000: December 15.

Present:  L’Heureux‑Dubé, Gonthier, McLachlin, Iacobucci, Major, Bastarache and Binnie JJ.

on appeal from the federal court of appeal

Patents – Claims construction – Whether “purposive construction”   proper approach to claims construction for both validity and infringement issues.

Patents – Validity – Double patenting – Whether patent should be invalid as double patenting.

In the 1970s the respondent Whirlpool developed an ingenious dual action agitator for clothes washing machines that utilized the bottom portion of the shaft for the usual oscillating motion back and forth but added an upper sleeve that was designed to work as a helical auger.  The auger rotated only in one direction like a post‑hole digger, and propelled water and clothing downwards onto the oscillating vanes of the lower agitator to produce more uniform scrubbing.  This development work resulted in three Canadian patents.  In the first patent the dual agitator was powered by a drive shaft.  A second patent (“'803 patent”) substituted a clutch mechanism for the drive shaft.  The trial judge concluded that both of these patents required that the vanes on the lower agitator be rigid.  Under a third patent (“'734 patent”) flexible vanes were substituted for rigid vanes.  The '734 patent also offered a choice of drive modes, one where the upper auger was driven “intermittently” and the other where it was driven “continuously”.  The trial judge held the '734 patent to be valid and infringed.

On appeal to the Federal Court of Appeal the centerpiece of the attack on the validity of the '734 patent was that it constituted “double patenting” because the invention set out in its intermittent drive claims corresponded with the invention set out in the claims of the earlier '803 patent.  Alternatively, it was said that the use of flex vanes was well understood in the washing machine business from the 1960s onward, and even if the '803 patent contemplated (as held by the trial judge) only rigid vanes on the lower oscillator, the use of flexible vanes was an obvious and non‑inventive variation that did not warrant patent protection.  Further the appellants denied infringement of the continuous drive claims.  The Federal Court of Appeal dismissed the appeal.

Held:  The appeal should be dismissed.

The first step in a patent suit is to construe the claims.  The “purposive construction” approach is adopted for both validity and infringement issues.  This requires the identification by the court, with the assistance of the skilled reader, of the particular descriptive words or phrases in the claims that describe the “essential” elements of the invention.  Purposive construction properly directs itself to the words of the claims interpreted knowledgeably and in the context of the specification as a whole; it advances the objective of an interpretation of the patent claims that is reasonable and fair to both patentee and public.

It was open to the trial judge to conclude, having regard to the expert evidence, that the claims of the '803 patent, properly construed, did not include flexible vanes.  The appellants “dictionary” approach to claims construction was rightly rejected.  It was permissible for the trial judge to look at the rest of the specification, including the drawing, to understand what was meant by the word “vane” in the claims, but not to enlarge or contract the scope of the claim as written and thus understood.  The patent specification was not addressed to grammarians, etymologists or to the public generally, but to skilled workers sufficiently versed in the art to which the patent relates to enable them on a technical level to appreciate the nature and description of the invention.  The trial judge, reading the claims with the knowledge and insight into the technical terms provided by the rest of the specification, and by the concession of the appellants’ own expert, concluded that rigid vanes were essential to the '803 invention as claimed.  No basis had been shown to reverse that conclusion.

The prohibition against double patenting involves a comparison of the claims rather than the disclosure, because it is the claims that define the monopoly.  The question is how “identical” the claims must be in the subsequent patent to justify invalidation.  The first branch of the prohibition is sometimes called “same invention”

double patenting.  Given the claims construction adopted by the trial judge it cannot be said that the subject matter of the '734 patent was the same or that the claims were “identical or conterminous” with those of the '803 patent.

There is, however, a second branch of the prohibition which is sometimes called “obviousness” double patenting.  This is a more flexible and less literal test that prohibits the issuance of a second patent with claims that are not “patentably distinct” from those of the earlier patent.  On this point, the trial judge was wrong to have accepted the evidence of a long-time employee of the respondent Whirlpool Corporation as a proxy for the “ordinary worker”.  His opinions were predicated on Whirlpool's in-house knowledge.  On the other hand the trial judge was entitled to reject the evidence of the appellants' expert whose testimony was not supported by the level of practical understanding of dual action washing machines that by 1981 was common knowledge among the skilled workers interested in this end of the washing machine business.  In the end, the trial judge concluded that he had not been given sufficient proof by the appellants to displace the presumption of validity in s. 45  of the Patent Act .  The Federal Court of Appeal agreed, and there is no basis on which this Court could properly interfere with the concurrent factual findings thus the validity of the '734 patent is affirmed.

Claims construction is a matter of law but whether a defendant's activities fall within the scope of the monopoly thus defined is a question of fact.  The trial judge erred in basing his finding of infringement of the continuous drive claims by conflating them to encompass the intermittent drive claims.  The error in claims construction was corrected by the Federal Court of Appeal.  The evidence of infringement was not very satisfactory.  The appellants declined to call a witness to describe the drive means utilized in the accused General Electric washing machines, preferring to sit back and argue that the respondents had not made sufficient proof.  Both the trial judge and the Federal Court of Appeal were obliged to fall back principally on a video showing a rotating General Electric auger under a “medium or light wash load”.  Unsatisfactory as the evidence was, the Federal Court of Appeal concluded that it supported the inference of a continuous drive as well as the observed continuous rotation.  In the absence of any evidence to the contrary, it was open to that court to find, as a fact, infringement of the continuous drive claims.  The appellants, having elected not to call any evidence on this point, were not well placed to argue that the Federal Court of Appeal made a palpable error in reaching the factual conclusion that it did.

Cases Cited

Applied:  Catnic Components Ltd. v. Hill & Smith Ltd., [1982] R.P.C. 183; O’Hara Manufacturing Ltd. v. Eli Lilly & Co. (1989), 26 C.P.R. (3d) 1; referred to: Consolboard Inc. v. MacMillan Bloedel (Sask.) Ltd., [1981] 1 S.C.R. 504; J. K. Smit & Sons, Inc. v. McClintock, [1940] S.C.R. 279; McPhar Engineering Co. of Canada v. Sharpe Instruments Ltd., [1956‑60] Ex. C.R. 467; Marconi v. British Radio Telegraph and Telephone Co. (1911), 28 R.P.C. 181; Birmingham Sound Reproducers Ld. v. Collaro Ld., [1956] R.P.C. 232; C. Van Der Lely N.V. v. Bamfords Ltd., [1963] R.P.C. 61; Dableh v. Ontario Hydro, [1996] 3 F.C. 751; Lister v. Norton Brothers and Co. (1886), 3 R.P.C. 199; Williams v. Box (1910), 44 S.C.R. 1; Rizzo & Rizzo Shoes Ltd. (Re), [1998] 1 S.C.R. 27; White v. Dunbar, 119 U.S. 47 (1886); Western Electric Co. v. Baldwin International Radio of Canada, [1934] S.C.R. 570; Metalliflex Ltd. v. Rodi & Wienenberger Aktiengesellschaft, [1961] S.C.R. 117; Burton Parsons Chemicals, Inc. v. Hewlett-Packard (Canada) Ltd., [1976] 1 S.C.R. 555; Ernest Scragg & Sons Ltd. v. Leesona Corp. (1964), 26 Fox Pat. C. 1; AT&T Technologies, Inc. v. Mitel Corp. (1989), 26 C.P.R. (3d) 238; Abbott Laboratories, Ltd. v. Nu-Pharm Inc. (1998), 78 C.P.R. (3d) 38; Free World Trust v. Électro Santé Inc., [2000] 2 S.C.R.  000, 2000 SCC 66; Beecham Canada Ltd. v. Procter & Gamble Co. (1982), 61 C.P.R. (2d) 1; Lovell Manufacturing Co. v. Beatty Bros. Ltd. (1962), 23 Fox Pat. C. 112; Commissioner of Patents v. Farbwerke Hoechst Aktiengesellschaft Vormals Meister Lucius & Bruning, [1964] S.C.R. 49; Beloit Technologies Inc. v. Valmet Paper Machinery Inc., [1997] R.P.C. 489; Jamb Sets Ltd. v. Carlton (1963), 42 C.P.R. 65, aff’d (1965), 46 C.P.R. 192; Submarine Signal Co. v. Henry Hughes & Son, Ld. (1931), 49 R.P.C. 149.

Statutes and Regulations Cited

Convention on the Grant of European Patents (European Patent Convention), October 5, 1973, art. 69.

Interpretation Act, R.S.C., 1985, c. I-21, ss. 2(1)  “regulation”, 12.

Patent Act, R.S.C. 1970, c. P-4, s. 10.

Patent Act, R.S.C., 1985, c. P-4, ss. 10  [rep. & sub. c. 33 (3rd Supp.), s. 2 ; rep. & sub. 1993, c. 15, s. 28], 34, 36(1), 44, 45, 46.

Authors Cited

Côté, Pierre-André.  The Interpretation of Legislation in Canada, 3rd ed.  Scarborough, Ont.: Carswell, 2000.

Fox, Harold G.  The Canadian Law and Practice Relating to Letters Patent for Inventions, 4th ed.  Toronto: Carswell, 1969.

Hayhurst, William L.  “The Art of Claiming and Reading a Claim”, in G. F. Henderson, ed., Patent Law of Canada.  Scarborough, Ont.: Carswell, 1994.

Hitchman, Carol V. E., and Donald H. MacOdrum.  “Don't Fence Me In:  Infringement in Substance in Patent Actions” (1990), 7 C.I.P.R. 167.

Vaver, David.  Intellectual Property Law: Copyright, Patents, Trade-marks.   Concord, Ont.: Irwin Law, 1997.

APPEAL from a judgment of Federal Court of Appeal (1999), 236 N.R. 330, 85 C.P.R. (3d) 129, [1999] F.C.J. No. 84 (QL), dismissing the appellants’ appeal from a decision of the Federal Court, Trial Division (1997), 76 C.P.R. (3d) 150, [1997] F.C.J. No. 1086 (QL), holding that patents 1,095,734 and 1,049,803 were valid, that patent 1,095,734 was infringed and that patent 1,049,803 was not infringed.  Appeal dismissed.

James D. Kokonis, Q.C.,  Dennis S. K. Leung and Ronald E. Dimock, for the appellants.

Christopher J. Kvas and Peter R. Everitt, for the respondents.

The judgment of the Court was delivered by

1                                   Binnie J. –  In 1975, the respondent Whirlpool Corporation announced to the world an advance in clothes washing technology which the trial judge described as “entirely new”.  The nub of the improvement was to replace the traditional one-piece “agitator” in the wash tub with a two-piece agitator consisting of a lower oscillating spindle with a rotating “auger” attached to the top.  By all accounts the two-piece “dual action” agitator produced a more effective wash (“uniform scrubbing”).  Whirlpool introduced these useful machines onto the North American market in the 1970s, and over the years sold millions of units to the clothes washing public.  General Electric (“GE”) and Maytag were somewhat envious of this invention, but moved quickly on expiry of the U.S. patents in 1995 to put their own dual action agitators on the market.  Between 1995 and the date of trial, GE had sold in excess of 750,000 dual action machines.  The respondents’ complaint is that the appellants' machines were not only marketed in the United States but some of them were sold in Canada where the relevant patents had not yet expired.

2                                   The development work at Whirlpool resulted in three patents.  Each, when issued, gave Whirlpool a 17-year monopoly on manufacturing and marketing washing machines that incorporated the inventions as respectively claimed.  The consumer market for large appliances is immense and this appeal brought together some of the major competitors for the purpose of alternatively denouncing or upholding the relevant patents owned by Whirlpool.  The appellants say that the first two patents to issue covered the invention, and that the monopoly was improperly extended by the issuance of the third patent (which at trial they were held to have infringed).  The third patent, the appellants say, ought for the most part never to have been granted and is to that extent invalid.

3                                   The practical impact of this argument is that if the most recent patent is invalid, the period of infringement is reduced by more than two years, and the compensation payable to Whirlpool would be greatly diminished.  The appeal raises some important legal issues concerning the interpretation, validity and infringement of patents, but in the end, the appellants' case largely comes apart on the evidence (or lack of it) and the appeal must therefore be dismissed.

I.  Facts

4                                   In the late 1960s, GE and its Canadian subsidiary, Camco marketed a range of washing machines across Canada that utilized what was known as a single action agitator, that is to say a single spindle sitting in a tub of water rotating its vanes back and forth to scrub the clothes.  Similar machines were marketed by the respondents Whirlpool and Inglis, and by the appellants in the companion appeal, Maytag Corporation and its Canadian subsidiaries.  The U.S. laboratories of the parent companies were at work trying to develop products that would give what advertising agencies call a “new and improved wash” to heavy household loads.  Progress was uneven.  Much research was done at Whirlpool and other manufacturers on the benefits of rigid vanes on the agitator versus flexible vanes (sometimes called “flex vanes”).  In the late 1960s, Whirlpool built a washer with flexible vanes for development purposes that mauled the clothes so badly it became known as the “Golden Gobbler”.  Maytag however developed a “flex vane” unitary action machine in the late 1960s and the trial judge noted the evidence that “[i]t's been nothing but a satisfactory device” over the next 30 years ((1997), 76 C.P.R. (3d) 150, at p. 182).  It did not tangle clothes unduly and was a great commercial success.  By the end of the 1960s, the clothes washing machine trade in North America was thus familiar with one-piece agitators featuring rigid or flexible vanes, and understood that the “yield” in the flex vanes could deliver an extra push to the laundry load to produce a better scrub.  Indeed, the evidence was that Maytag obtained a 50 percent increase in wash loads by using flexible vanes rather than rigid vanes.

5                                   Eventually, Whirlpool came up with an ingenious dual action agitator that utilized the bottom portion of the shaft for the usual oscillating motion back and forth in the wash cycle, but added an upper sleeve that was designed to work as a helical auger.  The auger rotated only in one direction like a post-hole digger, and propelled water and clothing downwards onto the oscillating vanes of the lower agitator which sent the laundry into a rollover tumble across the floor of the tub, upward along the side wall, thence back across the surface to the agitator (the “toroidal motion”). 

1.  Invention Dates

6                                   Whirlpool's initial invention of the dual action agitator was made in 1972 and resulted in Canadian patent 1,045,401 (the “'401 patent”).  It contemplated that both the upper and lower portions of the agitator would be powered by a drive shaft.  No claim was made against the appellants under the '401 patent.

7                                   In March 1973, a Whirlpool researcher, Ernest Ruble, came up with various ingenious improvements to the dual action agitator, including a new drive means that could be utilized to rotate the upper auger intermittently using a clutch that engaged when the lower agitator rotated forward and disengaged when it rotated backward.  The agitator sleeve itself was designed to be removable.  These advances resulted in a further application that eventually became Canadian patent 1,049,803 (the “'803 patent”).  The prototype washing machine had rigid vanes on the lower oscillating unit and when it went to the Whirlpool product development group for testing in mid to late 1973, it came under the eyes of Mr. John Pielemeier, an engineer with many years' experience.  Mr. Pielemeier was called as an expert at trial by Whirlpool.  His affidavit explained that:

My personal involvement with dual action agitators commenced in the middle to late portion of 1973 when I was an engineer in product engineering in the Whirlpool Laundry Engineering Division.  At that time Clark Platt presented to me, for the first time, a dual action agitator that had rigid vanes on its lower base.

8                                   The tests conducted by the product engineering group disclosed serious problems with the '803 technology.  It tangled up the clothes even worse than had the Golden Gobbler.  Counsel referred us to the following passage in Mr. Pielemeier's evidence:

It was the worst tangling I have ever seen in a machine.  As a matter of fact I had to stand on a chair to get the whole thing [i.e., the laundry test load] out of the machine. 

9                                   Mr. Kurt Werner, another Whirlpool engineer who joined the company somewhat later, described the problem to the trial judge thusly:

What we had done was taken this new clothes washing agitator that had this unidirectional motion and we were starting to see garments having a three-dimensional tangling condition, where garments were actually rotating around in the basket and actually rotating in the load and causing a roping effect within the load.

10                               Mr. Clark Platt was assigned to come up with a solution to the “3-D tangle” problem which he did by proposing the substitution of flex vanes for rigid vanes “at least as early as June 5, 1974" (trial judgment, at p. 154).  This work ultimately resulted in the third of the three patents, Canadian patent 1,095,734 (the “'734 patent”).  The “roping effect” was greatly reduced by making the vanes sufficiently flexible to yield and deflect the moving mass of water and laundry.  The benefit, apparently, lay in the ability of flex vanes to yield rather than in their ability to push, as disclosed in the '734 patent as follows:

This unloading of the vanes tends to avoid tangling of fabrics on the agitator which might otherwise lead to increased agitator shaft torque, increased motor wattage, reduced rollover as well as unbalanced spin loads and generally tangled clothes loads.

11                               The trial judge considered the 3-D tangling problem associated with “dual action” washers to be “qualitatively” different from the tangling experienced with such “unitary action” machines as the Golden Gobbler (at p. 183):

I would also note that, even after counsel's description of 3-D tangling and manual demonstration of what 3-D tangling is supposed to be, I remain unclear as to what this concept really means.  I am, however, prepared to accept that the tangling produced by dual action agitation is qualitatively different from that produced by unitary action agitation.

12                               Whirlpool also discovered that by use of gears and pinions the oscillating lower portion of the agitator could be made to rotate the upper auger continuously.  The '734 patent thus offered a choice of drive modes.  In one embodiment, the upper auger was driven “intermittently”; in another, it was driven continuously.

13                               The respondent Whirlpool Corporation applied for the U.S. equivalent of the '803 patent on November 23, 1973, despite Mr. Pielemeier's worry about the 3-D tangle problem.  By the time the Whirlpool Corporation filed an application for Canadian patent '803 on November 12, 1974, Whirlpool had come up with the solution of using flex vanes instead of rigid vanes, but did not in the '803 specification disclose the 3-D tangling problem.  Nor did Whirlpool disclose the flex vane solution that had been discovered five months before the Canadian '803 patent was applied for. 

14                               The claims of the '803 patent specify “vanes” but do not further specify whether the vanes are to be flexible or rigid.  Whirlpool's position is that flex vanes were not included.  The appellants argue the contrary.

15                               Whirlpool waited until June 16, 1976 to apply for what became the U.S. equivalent of the '734 patent for the dual agitator with flex vane and continuous drive claims.  The Canadian '734 patent was applied for on May 27, 1977.  Undoubtedly experimental and product development work continued between 1973 and 1976, but the result of the delay was to position a third patent to issue several years after the '401 and '803 patents.  Ultimately the result, if the '734 patent is valid, was to prolong the monopoly in Canada on the better type of dual action agitators from March 5, 1996 to February 16, 1998.  For ease of reference the relevant dates are as follows:

16                               It is of significance that all three patents were co-pending before the Commissioner of Patents for a period of almost two years between May 27, 1977, when the last of the three patent applications was filed with the Canadian Patent Office, and January 2, 1979, when the first of the three patents issued.  This is worth noting for two reasons.  Firstly, the 3-D tangle problem had in fact been disclosed in the '734 specification to the Commissioner of Patents, who was therefore in a position to consider any concern that the '803 technology lacked utility because of the 3-D tangle problems before the issuance of the '803 patent.  The '803 invention was nevertheless pronounced new, ingenious and useful and the '803 patent issued.  Secondly, s. 10 of the old Patent Act, R.S.C. 1970, c. P-4, provided that the contents of a patent specification are disclosed to the public only after a patent is issued.  The disclosure of “dual action” technology in the first two patent applications was not in the public domain until after the third patent had been applied for, and did not therefore constitute “prior art” to feed the appellants' “obviousness” attack on the '734 invention.

2.  The Claims in Suit

17                               The '803 patent taught a double action agitator with a drive system which the trial judge described as “unique”.  There was no drive shaft.  The upper part of the agitator was driven off the lower part by means of a clutch.  Claim 1 sets out the broad description of the claimed monopoly as follows:

1.    An agitator for a washing machine having a driven oscillating shaft, said agitator comprising:   first agitator portion capable of being mounted on said shaft by means of a locked, non-rotating connection and having an upper part, and a lower part provided with outwardly extending substantially vertically oriented vanes; a second agitator portion in the form of a sleeve having at least one outwardly extending, inclined vane, said sleeve being rotatably mounted on the upper part of the first agitator portion; and a one-way clutch located between the first and second agitator portions, the first agitator portion being adapted to drive said clutch and the second agitator portion being adapted to be driven by said clutch so that the rotation of the first agitator portion gives a positive rotation to the second agitator portion in only one direction of rotation of the first agitator portion, said inclined vane being inclined upwardly with respect to the direction of positive rotation of the second agitator portion, and at least the lower parts of said vertically oriented vanes extending radially outwardly by a greater amount than said at least one inclined  vane.  [Emphasis added.]

18                               The abstract of the patent refers to an “accessory comprising a sleeve which is securable to the barrel of the agitator . . . having a vane means attached thereto” (emphasis added).  Further, a portion of the '803 disclosure talks about an “agitator accessory . . . easily removable from the agitator itself” (emphasis added).  However, the claims themselves do not refer to the agitator sleeve as being either “securable” or removable, and it is the claims, not the rest of the specification, that define the monopoly. 

19                               At trial, the respondents and appellants were agreed that the GE machines with flex vanes were covered by the '803 patent.  They agreed that the only unresolved infringement issue under the '803 patent was whether or not “the element identified as a 'sleeve'” was removable.  As will be seen, the trial judge disagreed with both sides on the issue of claims construction.  He concluded that the '803 technology as claimed employed rigid vanes only.

20                               The appellants were also accused of infringing the '734 patent which explicitly stated that the vanes of the lower oscillator of the dual action agitator were flexible rather than rigid.  The '734 patent disclosed the new “continuous drive” claims.  Claim 1 set out the broad monopoly claim as follows:

1.  An agitator assembly for a clothes washing machine comprising:

a first agitator element,

a second agitator element,

drive means for driving said first agitator element in an oscillatory motion and for concurrently driving said second agitator element in an unidirectional rotary motion, said first and second agitator elements cooperating to circulate the contents of the machine in a toroidal rollover pattern within the washing machine, and means associated with said second agitator element for forcing articles adjacent thereto into the oscillatory path of said first agitator element and into said rollover pattern, said first agitator element having formed thereon flexible vanes which are free to flex in response to oscillatory motions of the agitator element, thereby to yieldingly engage fabrics deflected downwardly and lessening high impact loading of the first agitator element.  [Emphasis added.]

3.  The Litigation

21                               The appellants challenged the validity of both patents but adopted the fall-back position that if any infringement occurred, it was under the '803 patent.  This allowed them to argue that the '803 patent included the flex vanes and that (apart from the continuous drive claims) there was nothing “patentably distinct” to nourish the grant of the '734 patent.  It argued that the intermittent drive claims in the '734 patent constituted an illegitimate effort to prolong the monopoly by an unjustified two additional years.

22                               A similar action was subsequently initiated against Maytag and its Canadian subsidiaries.  The claims against GE included both the “intermittent” drive claims and the “continuous” drive claims.  The action against Maytag asserted only the intermittent claims.

23                               The GE action proceeded to trial, it being agreed that the outcome of the GE action would govern the Maytag action as well, including all findings of fact and law at trial.  The appeals were heard concurrently in the Federal Court of Appeal and in this Court. 

II.  Judicial History

1.  Federal Court, Trial Division  (1997), 76 C.P.R. (3d) 150

(a)  The '803 Patent

24                               As stated, the parties had agreed in advance that infringement of the '803 claims, as they interpreted them, turned on whether the agitator “sleeve” was removable.  The respondents claimed that it was and the appellants denied it.  This issue was addressed by the experts, including a video of the Whirlpool expert attempting to remove the GE sleeve with power tools, apparently with limited success.  Cullen J. found that the sleeve was not removable but went on to hold that this was not the essence of the '803 invention.  In his view, the essence of the '803 patent was the unique drive mechanism connecting the lower agitator to the upper auger without the use of a drive shaft.  The trial judge noted that the '803 patent was not attacked until some 16 years after it was issued and therefore the "onus on the defendant to prove invalidity ought to be a heavy one because the patent has been honoured for so long as valid" (p. 166).  He rejected the various attacks on the validity of the patent including over-breadth, covetousness and obviousness.  He held the '803 patent to be valid.

25                               Cullen J. ruled that there was no infringement however because, in his view, rigid vanes were an essential component of the '803 invention as claimed.  The accused GE machines used flex vanes.  Accordingly, Cullen J. held the '803 patent to be valid but not infringed.  If he had found infringement, it would have ceased with expiry of the '803 patent on March 5, 1996.

(b)  The '734 Patent

26                               As to validity, the trial judge concluded that the '734 patent was for a new and different invention than the '803 patent, because it addressed specifically the superiority of flex vanes over rigid vanes for the oscillating agitator, an invention that he thought was not rendered obvious and therefore non-patentable by the '803 patent.  So construed, the '734 patent did not violate the prohibition on “double patenting”.  With respect to the intermittent and continuous drive claims, Cullen J. held, at p. 176, that:

These two claims seem to describe two different, possible embodiments of the drive means of the invention.  According to this analysis, both intermittent and continuous drive means are envisaged.  It is even possible to include in this equation a drive means that is both intermittent and continuous.  That is, one may have a “continuously intermittent” motion, where during the operation of the machine, the motion of the upper auger may continuously be driven or rotated in intermittent pauses or spurts.  [Emphasis in original.]

27                               With respect to infringement, the trial judge concluded that the appellants' machines did infringe the flex vane monopoly including both the intermittent drive claims and the “continuous drive” claims.  As to whether the upper auger was made to rotate continuously in the GE tub, he said, at p. 176:

. . . I do not believe that the plaintiffs' argument about the motion of the upper portion of the defendants' agitator goes to the heart of the matter.  It is not necessary to show that the drive in the medium or light load is strictly continuous.  As long as the movement is not sporadic, it may very well have been contemplated to fall within the scope of the claims of the invention.  To my mind, this is the type of motion – and not a strictly continuous motion – that was demonstrated in Mr. Werner's videotaped evidence. 

28                               Accordingly, he held the continuous drive claims to be infringed.  In the result, he gave judgment for Whirlpool with an injunction against the appellants' future infringement of the '734 patent plus compensation for past infringement by way of damages or an accounting of profits, as the respondents may elect.

2.  Federal Court of Appeal (1999), 85 C.P.R. (3d) 129

29                               The appellants did not appeal the dismissal of its claim for a declaration of invalidity of the '803 patent, and specifically disclaimed in its notice of appeal any challenge to Cullen J.'s ruling that the '803 patent was not infringed.  No cross-appeal was taken by the respondents on the '803 infringement ruling.  Accordingly, the only issues in play were the validity and infringement of the '734 patent.

30                               With respect to onus, Stone J.A. noted the trial judge had erred in saying that passage of time without challenge created a "heavy onus" on the party attacking the validity of a patent.  However, in reading the trial judgment as a whole, he accepted that the trial judge had in fact applied the proper civil standard on a balance of probabilities.

31                               With respect to the validity of the '734 patent, Stone J.A. rejected the attack based on double patenting.  He held that double patenting requires that the claims of the later patent be conterminous with the claims in the earlier patent, or that the latter is an obvious and uninventive extension of the former.  Neither was the case here.  He also rejected the attacks based on covetousness and affirmed the validity of the '734 patent.

32                               Stone J.A. upheld the trial judge's finding that the flexible vanes fitted to the agitators of the GE machines infringed the '734 patent.  With respect to infringement of the "continuous drive" claims, he was puzzled by the trial judge's finding, at p. 194, that "the upper auger can be continuously rotated, albeit in intermittent pauses, in one direction".  The members of the Federal Court of Appeal viewed the videotaped evidence of the dual action agitator in operation and concluded that “the motion of the upper element of the appellants' product while working under medium and light load conditions was continuous” (pp. 141-42).  Notwithstanding the equivocal conclusion reached by the trial judge, Stone J.A. said (at p. 142) that “the motion shown on the exhibit speaks for itself”.  In the result, the trial judgment was upheld and the appeal dismissed.

III.  Relevant Statutory Provisions

33                               As the patents in suit were issued prior to October 1, 1989, the provisions of the former Patent Act  apply.  The relevant sections of the Patent Act, R.S.C., 1985, c. P-4 , provide as follows:

Section 34.  [Specification]

(1)  An applicant shall in the specification of his invention

(a)  correctly and fully describe the invention and its operation or use as contemplated by the inventor;

(b)  set out clearly the various steps in a process, or the method of constructing, making, compounding or using a machine, manufacture or composition of matter, in such full, clear, concise and exact terms as to enable any person skilled in the art or science to which it appertains, or with which it is most closely connected, to make, construct, compound or use it;

(c)  in the case of a machine, explain the principle thereof and the best mode in which he has contemplated the application of that principle;

(d)  in the case of a process, explain the necessary sequence, if any, of the various steps, so as to distinguish the invention from other inventions; and

(e)  particularly indicate and distinctly claim the part, improvement or combination that he claims as his invention.

(2)  Claims to be stated distinctly – The specification referred to in subsection (1) shall end with a claim or claims stating distinctly and in explicit terms the things or combinations that the applicant regards as new and in which he claims an exclusive property or privilege.

Section 36.  [Patent for One Invention Only]

(1)  A patent shall be granted for one invention only but in an action or other proceeding a patent shall not be deemed to be invalid by reason only that it has been granted for more than one invention.

Section 44.  [What Patent Shall Contain and Confer]

Every patent granted under this Act shall contain the title or name of the invention, with a reference to the specification, and shall, subject to the conditions prescribed in this Act, grant to the patentee and his legal representatives for the term therein mentioned, from the granting of the patent, the exclusive right, privilege and liberty of making, constructing, using and vending to others to be used the invention, subject to adjudication in respect thereof before any court of competent jurisdiction.

Section 45 .  [Presumption of Validity]

Every patent granted under this Act shall be issued under the signature of the Commissioner and the seal of the Patent Office, shall bear on its face the date on which it is granted and issued and shall thereafter, in the absence of any evidence to the contrary, be valid and avail the grantee and his legal representatives for the term mentioned therein.

Section 46.  [Term of Patent]

The term limited for the duration of every patent issued by the Patent Office under this Act shall be seventeen years from the date on which the patent is granted and issued.

34                               The relevant amended provision of the Patent Act, R.S.C., 1985, c. P-4 , as amended by S.C. 1993, c. 15, provide as follows:

Section 10 .  [Inspection by the Public]

(1)  Subject to subsections (2) to (6) and section 20, all patents, applications for patents and documents filed in connection with patents or applications for patents shall be open to public inspection at the Patent Office, under such conditions as may be prescribed.

(2)  Confidentiality period – Except with the approval of the applicant, an application for a patent, or a document filed in connection with the application, shall not be open to public inspection before a confidentiality period of eighteen months has expired.

(3)  Beginning of confidentiality period – The confidentiality period begins on the filing date of the application or, where a request for priority has been made in respect of the application, it begins on the earliest filing date of any previously regularly filed application on which the request is based.

IV.  Analysis

35                               A dispute over the internal workings of a washing machine is unlikely to fire everyone’s imagination but, as with many intellectual property disputes, raises important legal issues and significant financial stakes.

36                               Counsel for the respondents claims that his clients produced works of great ingenuity “if not genius”, and that the three patents were properly given in exchange for disclosure of these meritorious inventions.  Counsel for the appellants suggest that while “dual action” washing machines represented a useful advance on the prior art, Whirlpool was properly rewarded for its invention by the award of the '401 and '803 patents.  Award of a third patent was excessive.

37                               It is common ground that the bargain between the patentee and the public is in the interest of both sides only if the patent owner acquires real protection in exchange for disclosure, and the public does not for its part surrender a more extended monopoly than the statutory 17 years from the date of the patent grant (now 20 years from the date of the filing of the patent application).  A patentee who can "evergreen" a single invention through successive patents by the expedient of obvious or uninventive additions prolongs its monopoly beyond what the public has agreed to pay.  The issue is whether Whirlpool's '734 patent falls into that condemned category.

38                               The centrepiece of the attack by the appellants on the validity of the '734 patent is that the '734 patent constitutes “double patenting” because the invention set out in its intermittent drive claims corresponds with the invention set out in the claims of the earlier '803 patent.  Alternatively, it was said that the use of flex vanes was well understood in the washing machine business from the 1960s onward, and even if the '803 patent contemplated (as held by the trial judge) only rigid vanes on the lower oscillator, the use of flexible vanes was an obvious and non-inventive variation that did not warrant patent protection.  Either way, they say, the '734 patent is invalid.

39                               The source of the error in the courts below, according to the appellants, is the approach to claims construction which the Federal Court has developed based initially on a misunderstanding and misapplication of the “purposive construction” approach formulated by the House of Lords in Catnic Components Ltd. v. Hill & Smith Ltd., [1982] R.P.C. 183.  The appellants say the Catnic decision “has had a detrimental impact throughout the Commonwealth jurisdictions, and in particular to a proper understanding of the common law of claim construction in Canada”.  The appellants invite the Court to reject the Catnic approach, and to overrule the Federal Court cases that follow it, particularly O’Hara Manufacturing Ltd. v. Eli Lilly & Co. (1989), 26 C.P.R. (3d) 1 (F.C.A.).  In this respect, however, I agree with the observation of William L. Hayhurst, Q.C., that “[p]urposive construction is nothing new, though Lord Diplock is credited with first using the expression in patent cases” (see Hayhurst, “The Art of Claiming and Reading a Claim” in Patent Law of Canada (1994), edited by G. F. Henderson, Q.C., at p. 193).

40                               The appellants, however, invite the Court to return to what they call a “plain and unambiguous” meaning approach to claims construction.  The plain and unambiguous meaning of the word “vane” in the '803 patent, they say, is satisfied by either a flex vane or a rigid vane.  Adoption of the Catnic “purposive construction” approach at the initial stage of claims construction injects factual issues that are more appropriately left to the infringement analysis.  If the attack on the validity of the '734 patent fails, the appellants seek a reversal of the finding that they infringed the “continuous drive” claims of the '734 patent.  They do not dispute infringement of the “intermittent” drive claims.

41                               These arguments resolve themselves into the following issues:

1.    What are the relevant principles of patent claims construction?

2.    Do the claims of the '803 patent, properly construed, include flexible vanes?

3.    If the '803 patent claims properly construed do not include flex vanes, is the '734 patent nevertheless invalid because of double patenting?

4.    If not, are the appellants liable for infringement of the “continuous drive” claims?

1.  The Principles of Patent Claims Construction

42                               The content of a patent specification is regulated by s. 34  of the Patent Act .  The first part is a “disclosure” in which the patentee must describe the invention “with sufficiently complete and accurate details as will enable a workman, skilled in the art to which the invention relates, to construct or use that invention when the period of the monopoly has expired”:  Consolboard Inc. v. MacMillan Bloedel (Sask.) Ltd., [1981] 1 S.C.R. 504, at p. 517.  The disclosure is the quid provided by the inventor in exchange for the quo of a 17-year (now 20-year) monopoly on the exploitation of the invention.  The monopoly is enforceable by an array of statutory and equitable remedies and it is therefore important for the public to know what is prohibited and where they may safely go while the patent is still in existence.  The public notice function is performed by the claims that conclude the specification and must state “distinctly and in explicit terms the things or combinations that the applicant regards as new and in which he claims an exclusive property or privilege” (s. 34(2) )”.  An inventor is not obliged to claim a monopoly on everything new, ingenious and useful disclosed in the specification.  The usual rule is that what is not claimed is considered disclaimed.

43                               The first step in a patent suit is therefore to construe the claims.  Claims construction is antecedent to consideration of both validity and infringement issues.  The appellants' argument is that these two inquiries – validity and infringement – are distinct, and that if the principles of  “purposive construction” derived from Catnic are to be adopted at all, they should properly be confined to infringement issues only.  The principle of  “purposive construction”, they say, has no role to play in the determination of validity, and its misapplication is fatal to the judgment under appeal.

44                               It is true that in Catnic itself there was no attack on the validity of the patent.  The litigation turned on issues of infringement.  The patent in issue dealt with galvanized steel lintels for use in building construction.  Lintels are structural members placed over openings such as doors and windows to support the building above.  The patent taught an ingenious new type of lintel of sheet metal bent into a box-like “lazy Z” shape that was light to handle and inexpensive to manufacture.  The defendant knew of the plaintiff's product but was not familiar with the plaintiff's patent.  The claims (of which they were unaware) taught that the lintel must have “a second rigid support member extending vertically from or from near the rear edge of the first horizontal plate” (underlining added; italics in original deleted).  Vertical alignment would maximize the load-bearing capacity.  For reasons unrelated to patent avoidance, the rigid support member in the defendant's product was inclined about eight degrees off vertical.  The trial judge concluded that there was no literal infringement because the support did not extend precisely “vertically”, but that, since there was no material difference in function of the component part, there was, viewing the defendant's lintel as a whole, infringement of the “pith and marrow” of the plaintiff's invention.  The trial judge was reversed by a majority in the Court of Appeal but was subsequently avenged by restoration of his judgment by a unanimous House of Lords.  Lord Diplock's description of purposive construction was as follows, at pp. 242-43:

My Lords, a patent specification is a unilateral statement by the patentee, in words of his own choosing, addressed to those likely to have a practical interest in the subject matter of his invention (i.e. “skilled in the art”), by which he informs them what he claims to be the essential features of the new product or process for which the letters patent grant him a monopoly.  It is those novel features only that he claims to be essential that constitute the so-called “pith and marrow” of the claim.  A patent specification should be given a purposive construction rather than a purely literal one derived from applying to it the kind of meticulous verbal analysis in which lawyers are too often tempted by their training to indulge.  The question in each case is:  whether persons with practical knowledge and experience of the kind of work in which the invention was intended to be used, would understand that strict compliance with a particular descriptive word or phrase appearing in a claim was intended by the patentee to be an essential requirement of the invention so that any variant would fall outside the monopoly claimed, even though it could have no material effect upon the way the invention worked.  [Emphasis in original.]

45                               The key to purposive construction is therefore the identification by the court, with the assistance of the skilled reader, of the particular words or phrases in the claims that describe what the inventor considered to be the “essential” elements of his invention.  This is no different, I think, than the approach adopted roughly 40 years earlier by Duff C.J. in J. K. Smit & Sons, Inc. v. McClintock, [1940] S.C.R. 279.  The patent in that case related to a method of setting diamonds in devices such as rotary drill bits for earth boring.  Duff C.J., citing the earlier jurisprudence, put the focus on the inventor's own identification of the “essential” parts of his invention, at p. 285:

Obviously, the invention, as described by the inventor himself, involves the use of air suction to hold the diamonds in place while the molten metal is being introduced into the mold.  There can be no doubt, in my mind, that as the inventor puts it, that is an essential part of his process.  That part of his process is clearly not taken by the appellants.  Adapting the language of Lord Romer, it is not the province of the court to guess what is and is not of the essence of the invention of the respondent.  The patentee has clearly indicated that the use of air suction at that stage of the process is an essential, if not the essential, part of the invention described in the specification.  [Emphasis added.]

46                               To the same effect is the judgment of Thorson P. in McPhar Engineering Co. of Canada v. Sharpe Instruments Ltd., [1956-60] Ex. C.R. 467, at p. 525:

Thus it is established law that if a person takes the substance of an invention he is guilty of infringement and it does not matter whether he omits a feature that is not essential to it or substitutes an equivalent for it.  [Emphasis added.]

47                               The “essential” elements approach was established in earlier English cases such as Marconi v. British Radio Telegraph and Telephone Co. (1911), 28 R.P.C. 181 (Ch. D.), at p. 217, referred to by Duff C.J. in J. K. Smit, supra, and more recent pre-Catnic decisions in that country such as Birmingham Sound Reproducers Ld. v. Collaro Ld., [1956] R.P.C. 232 (Eng. C.A.), and C. Van Der Lely N.V. v. Bamfords Ltd., [1963] R.P.C. 61 (H.L.), where Lord Reid, dissenting on the result, said at p. 76:  “you cannot avoid infringement by substituting an obvious equivalent for an unessential integer” (emphasis added).

48                               The Catnic analysis therefore was not a departure from the earlier jurisprudence in the United Kingdom or in this country.  It is no disrespect to Lord Diplock to suggest that at least to some extent he poured some fine old whiskies into a new bottle, skilfully refined the blend, brought a fresh clarity to the result, added a distinctive label, and voilà “purposive construction”.  In Catnic, as in the earlier case law, the scope of the monopoly remains a function of the written claims but, as before, flexibility and fairness is achieved by differentiating the essential features (“the pith and marrow”) from the unessential, based on a knowledgeable reading of the whole specification through the eyes of the skilled addressee rather than on the basis of “the kind of meticulous verbal analysis in which lawyers are too often tempted by their training to indulge” (Catnic, supra, p. 243).

49                               As stated, the Federal Court of Appeal applied the “purposive construction” approach to claims construction in O'Hara, supra, and, with respect, I think it was correct to do so.  The appellants' argument that the principle of purposive construction is wrong or applies only to infringement issues must be rejected for a number of reasons:

(a)   While Catnic, supra, dealt with infringement, the court had first to determine the scope and content of the plaintiff's invention.  Lord Diplock was careful to relate his discussion of the “essential” features to the wording of the claims.  It was these essential features considered without reference to specific issues of validity or infringement that constituted the “pith and marrow of the claim”.  He canvassed the possible existence of “any variant” of a “particular descriptive word or phrase appearing in a claim” but was careful not to link his discussion of claims construction to the particular variant in the defendant's allegedly infringing lintel.  Indeed, for emphasis, he italicized the word “any” in “any variant”.  A patent must not of course be construed with an eye on the allegedly infringing device in respect of infringement or with an eye to the prior art in respect of validity to avoid its effect:  Dableh v. Ontario Hydro, [1996] 3 F.C. 751 (C.A.), at pp. 773-74.  Claims construction cannot be allowed to become a results-oriented interpretation, but there is nothing in Lord Diplock's speech that would support such an erroneous approach.

(b)   Acceptance of the appellants' argument could result in a different claims construction for the purpose of validity than for the purpose of infringement (assuming purposeful construction is retained for infringement issues).  However, it has always been a fundamental rule of claims construction that the claims receive one and the same interpretation for all purposes. 

(c)   The orthodox rule is that a patent “must be read by a mind willing to understand, not by a mind desirous of misunderstanding”, per Chitty J. in Lister v. Norton Brothers and Co. (1886), 3 R.P.C. 199 (Ch. D.), at p. 203.  A “mind willing to understand” necessarily pays close attention to the purpose and intent of the author.

(d)   Rejection of “purposeful construction” would imply the embrace of a purposeless approach that ignores the context and use to which the words are being put.  Purposeless construction was rejected by this Court long before Catnic, supra, as in Williams v. Box (1910), 44 S.C.R. 1, per Idington J., at p. 10:

If we would interpret correctly the meaning of any statute or other writing we must understand what those framing it were about, and the purpose it was intended to execute.  [Emphasis added.]

(e)   In fact, a patent is more than just “other writing”.  The words of the claims are initially proposed by the applicant, but they are thereafter negotiated with the Patent Office, and in the end are accepted by the Commissioner of Patents as a correct statement of a monopoly that can properly be derived from the invention disclosed in the specification.  When the patent issues, it is an enactment within the definition of “regulation” in s. 2(1)  of the Interpretation Act, R.S.C., 1985, c. I-21 , which says:

“regulation” includes an order, regulation, rule, rule of court, form, tariff of costs or fees, letters patent, commission, warrant, proclamation, by-law, resolution or other instrument issued, made or established

(a)  in the execution of a power conferred by or under the authority of an Act, or

(b)  by or under the authority of the Governor in Council;  [Emphasis added.]

A patent must therefore be given such interpretation according to s. 12  of the Interpretation Act  “as best ensures the attainment of its objects”.  Intention is manifested in words, whose meaning should be respected, but words themselves occur in a context that generally provides clues to their interpretation and a safeguard against their misinterpretation.  P.-A. Côté, in The Interpretation of Legislation in Canada (3rd ed. 2000), puts the matter succinctly when he writes, at p. 387, “Meaning flows at least partly from context, of which the statute's purpose is an integral element” (emphasis added).  To the same effect see Rizzo & Rizzo Shoes Ltd. (Re), [1998] 1 S.C.R. 27, at para. 21.  These principles apply to claims construction by virtue of the Interpretation Act .

(f)    While the appellants express concern that “purposive construction” may open the door to extrinsic evidence of intent, as is the case with certain types of extrinsic evidence in the United States, neither Catnic, supra, nor O'Hara, supra, goes outside the four corners of the specification, and both properly limit themselves to the words of the claims interpreted in the context of the specification as a whole.

(g)   While “purposive construction” is a label introduced into claims construction by Catnic, supra, the approach itself is quite consistent, in my view, with what was said by Dickson J. the previous year in Consolboard, supra, on the topic of claims construction, at pp. 520-21:

We must look to the whole of the disclosure and the claims to ascertain the nature of the invention and methods of its performance, (Noranda Mines Limited v. Minerals Separation North American Corporation, [1950] S.C.R. 36), being neither benevolent nor harsh, but rather seeking a construction which is reasonable and fair to both patentee and public.  There is no occasion for being too astute or technical in the matter of objections to either title or specification for, as Duff C.J.C. said, giving the judgment of the Court in Western Electric Company, Incorporated, and Northern Electric Company v. Baldwin International Radio of Canada, [1934] S.C.R. 570, at p. 574, "where the language of the specification, upon a reasonable view of it, can be so read as to afford the inventor protection for that which he has actually in good faith invented, the court, as a rule, will endeavour to give effect to that construction".

Not only is “purposive construction” consistent with these well-established principles, it advances Dickson J.'s objective of an interpretation of the patent claims that “is reasonable and fair to both patentee and public”. 

(h)   The appellants suggest that “purposive construction” undermines the public notice function of the claims, and unfairly handicaps legitimate competition.  The trial judge, they say, was able to salvage the '734 patent by narrowing the scope of the word “vane” in the earlier '803 patent by a restrictive “purposive” construction.  However, purposive construction is usually criticized by accused infringers for tending to expand the written claims.  In fact, purposive construction can cut either way.  Here it enabled the appellants to escape infringement of the '803 patent.  No doubt if the '734 patent had never been granted, the appellants would now be strongly advocating a narrow “purposive construction” of the '803 patent, and of course the respondents would just as surely be advocating the contrary position.  Purposive construction is capable of expanding or limiting a literal text, as Hayhurst, supra, points out at p. 194 in words that anticipate the trial judgment in this case:

Purposive construction may show that something that might literally be within the scope of the claim was not intended to be covered, so that there can be no infringement. . .

Similarly, two other experienced practitioners, Carol V. E. Hitchman and Donald H. MacOdrum have concluded that "[a] purposive construction is not necessarily a broader construction than a purely literal one, although it may be" (Hitchman and MacOdrum, “Don't Fence Me In:  Infringement in Substance in Patent Actions” (1990), 7 C.I.P.R. 167, at p. 202). 

50                               While the Catnic approach to claims construction has subsequently been held in England to be compatible with Article 69 of the European Patent Convention, it was not decided with reference to the Convention.  O'Hara, supra, does not represent a stealthy incorporation of the Convention into Canadian law.  Indeed, as I have endeavoured to show, purposive construction has long been a theme in Canadian patent law, albeit not under that label.

2.  Do the Claims of the '803 Patent, Properly Construed, Include Flexible Vanes?

51                               In the present case, the appellants seek a broad interpretation of the word “vane” in the '803 patent claims.  It is unusual, of course, to have accused infringers arguing for a broad interpretation of the patent claims under which they have been charged.  It is equally unusual for a patent owner to be demanding a narrow interpretation.  The unusual role reversal is dictated by the appellants' desire to broaden the '803 patent to set up their argument for the invalidity of the later '734 patent.  They contend that the plain unvarnished meaning of the word “vane” standing on its own in claims 1 and 2 of the '803 patent must, as a matter of language, include both flexible vanes and rigid vanes and that there is no call or entitlement to supplement the verbal analysis by reference to “purpose” or anything else.  They plead in aid the “nose of wax” metaphor offered in the last century by the U.S. Supreme Court:

Some persons seem to suppose that a claim in a patent is like a nose of wax which may be turned and twisted in any direction, by merely referring to the specification, so as to make it include something more than, or something different from, what its words express. . . .  The claim is a statutory requirement, prescribed for the very purpose of making the patentee define precisely what his invention is; and it is unjust to the public, as well as an evasion of the law, to construe it in a manner different from the plain import of its terms.

(White v. Dunbar, 119 U.S. 47 (1886), at pp. 51-52, per Bradley J.)

52                               I have already given my reasons for concluding that to the extent the appellants are arguing for a simple “dictionary” approach to construction of the '803 claims, it must be rejected.  In Western Electric Co. v. Baldwin International Radio of Canada, [1934] S.C.R. 570, the Court cited earlier authority dealing with the word "conduit" as used in a patent claim.  Duff C.J. at p. 572 accepted the proposition that “[y]ou are not to look into the dictionary to see what 'conduit' means, but you are to look at the specification in order to see the sense in which the patentees have used it”.  In Consolboard, supra, as mentioned, Dickson J. considered that the whole of the specification (including the disclosure and the claims) should be looked at “to ascertain the nature of the invention” (p. 520).  To the same effect is the statement of Taschereau J. in Metalliflex Ltd. v. Rodi & Wienenberger Aktiengesellschaft, [1961] S.C.R. 117, at p. 122:

The claims, of course, must be construed with reference to the entire specifications, and the latter may therefore be considered in order to assist in apprehending and construing a claim, but the patentee may not be allowed to expand his monopoly specifically expressed in the claims “by borrowing this or that gloss from other parts of the specifications”.

More recently, Hayhurst, supra, at p. 190, cautioned that "[t]erms must be read in context, and it is therefore unsafe in many instances to conclude that a term is plain and unambiguous without a careful review of the specification".  In my view, it was perfectly permissible for the trial judge to look at the rest of the specification, including the drawing, to understand what was meant by the word “vane” in the claims, but not to enlarge or contract the scope of the claim as written and thus understood.

53                               A second difficulty with the appellants' dictionary approach is that it urges the Court to look at the words through the eyes of a grammarian or etymologist rather than through the eyes and with the common knowledge of a worker of ordinary skill in the field to which the patent relates.  An etymologist or grammarian might agree with the appellants that a vane of any type is still a vane.  However, the patent specification is not addressed to grammarians, etymologists or to the public generally, but to skilled individuals sufficiently versed in the art to which the patent relates to enable them on a technical level to appreciate the nature and description of the invention:  H. G. Fox, The Canadian Law and Practice Relating to Letters Patent for Inventions (4th ed. 1969), at p. 185.  The court, writes Dr. Fox, at p. 203, must place itself

in the position of some person acquainted with the surrounding circumstances as to the state of the art and the manufacture at the time, and making itself acquainted with the technical meaning in that art or manufacture that any particular word or words may have.

See also D. Vaver, Intellectual Property Law (1997), at p. 140.  Knowledge of purpose is one of the important attributes the skilled worker brings to the exercise, as was made clear in Burton Parsons Chemicals, Inc. v. Hewlett-Packard (Canada) Ltd., [1976] 1 S.C.R. 555, a case that concerned the validity of a chemical patent.  The invention was a type of conductive cream to be smeared on bits of the human body for the purpose of making electro-cardiograms and the like.  The mixture was of no fixed composition.  The essential invention was “to combine a highly ionizable salt with an aqueous emulsion” (p. 564).  It was put in evidence that hundreds, if not thousands, of substances would fit the description, including some that would be toxic or irritating to the skin.  A toxic “conductive cream” would not be a useful therapeutic tool, and it was alleged on that account that the patent lacked utility and was invalid.  These objections were swept away by Pigeon J. who held that the notional skilled workman would understand perfectly well the purpose of the combination and could therefore be expected to apply the teaching of the patent by sensibly choosing components suitable for that purpose (p. 563):

While the construction of a patent is for the Court, like that of any other legal document, it is however to be done on the basis that the addressee is a man skilled in the art and the knowledge such a man is expected to possess is to be taken into consideration.  To such a man it must be obvious that a cream for use with skin contact electrodes is not to be made up with ingredients that are toxic or irritating, or are apt to stain or discolour the skin.

Burton Parsons is a pre-Catnic instance of purposive construction where, as in Catnic itself, the skilled addressee made sense and purpose of the words used in the claim by deploying the common knowledge of someone in that position.  It is through the eyes of such a person, not an etymologist or academic grammarian, that the terms of the specification, including the claims, must be read.

54                               The argument in this case turns on the meaning of the expression “outwardly extending substantially vertically oriented vanes” (emphasis added).  All parties agree that the '803 specification, including claims, is silent on the type of vane (rigid or flexible) to be used in the lower oscillating portion of the agitator, except that the drawing of the preferred embodiment of the invention appended to the patent specification appears to show rigid vanes.  “Reference to the patent drawings will sometimes clarify what is meant by a claim”:  Hayhurst, supra, at p. 190; see also Fox, supra, at p. 220.  The drawing is of limited help but hardly conclusive because the '803 disclosure makes it clear that the drawing represents a preferred embodiment but does not necessarily exhaust the invention.  The issue for the trial judge, accordingly, was whether, at the date of issuance of the '803 patent, a person skilled in the art of clothes washing machines would have understood from a reading of the claims, together with any definitional assistance from the rest of the specification, that “vanes” must be of a particular type, and if so which type, rigid or flexible.

55                               I say “at the date of issuance of the '803 patent” because some cases suggest that the claims ought to be construed in light of the relevant knowledge at the earlier date of the invention:  Ernest Scragg & Sons Ltd. v. Leesona Corp. (1964), 26 Fox Pat. C. 1 (Ex. Ct.), per Thorson P., at p. 43, or on the date the patent application was filed:  AT&T Technologies, Inc. v. Mitel Corp. (1989), 26 C.P.R. (3d) 238 (F.C.T.D.), at p. 260.  The possible choices of the priority date (where a Canadian application is based on a foreign filing), the Canadian filing date, the publication date or the issuance (or “grant”) date, have created some uncertainty:  Abbott Laboratories, Ltd. v. Nu-Pharm Inc. (1998), 78 C.P.R. (3d) 38 (F.C.T.D.), at p. 50.  In the case of pre-October 1989 patent filings in Canada, one at least had the comfort of knowing that the date of publication and the date of issue were the same.  For the reasons given in the accompanying decision in Free World Trust v. Électro Santé Inc., [2000] 2 S.C.R. 000, 2000 SCC 66, at para. 54, my view is that the language of a patent should be construed as of the date of publication, which in the case of this pre-1989 patent was, to repeat, the date of issue:  Western Electric, supra, at p. 582, per Duff C.J.;  Burton Parsons, supra, per Pigeon J., at p. 560 (“la date de la délivrance du brevet” in the more specific French language text); Consolboard, supra, at p. 523; Fox, supra, at pp. 206-7.  The critical date is important here because the appellants' double patenting argument presupposes that when the '734 patent was issued on February 17, 1981 it was obvious and uninventive to substitute flex vanes for rigid vanes on a dual action agitator.  The obviousness argument would have been more tenuous as of the date of the invention almost 7 years earlier (“at least as early as June 5, 1974”), or even the date of the filing of the '734 patent application in Canada (May 27, 1977). 

56                               Under the new Patent Act  (S.C. 1993, c. 15, s. 28), the critical date would be the date of publication which, pursuant to s. 10 , would be no earlier than 18 months after the effective date of the application unless abridged with the approval of the applicants.  The “effective date” in the case of a Canadian patent application based on a foreign patent application would be its priority date or the filing date of the international application.  The fact the patents at issue in this case took 4 to 5 years from Canadian filing to Canadian issuance underlines the significance of the new accelerated 18-month “laid open” date.

57                               The third and most important obstacle to the appellants' dictionary approach is that it was not in fact consistent with the testimony of their own expert.  The parties called three experts.  The role of the expert was not to interpret the patent claims but to put the trial judge in the position of being able to do so in a knowledgeable way.

58                               The trial judge accepted the view of the expert called by the appellants, a retired Maytag engineer named Mr. John Mellinger, who testified that the word “vane” in claim 1 would be understood by the skilled reader of the '803 patent as a reference to a rigid vane:

And the vanes that were disclosed by Mr. Platt [applicant for the '803 patent] at that time were rigid vanes at the bottom.  That was all that he really referred to, it's already pictured, didn't describe anything else.

59                               The two experts called by the respondents were more equivocal.  Mr. Werner, a lead development engineer at Whirlpool, understood from a reading of the '803 specifications that “flexible vanes would be permitted, they are not excluded, but they are not required”.  Mr. John Pielemeier, another Whirlpool engineer, thought the use of flex vanes was not taught by the '803 patent and that such an interpretation would be “theoretical” rather than practical.

Q.   . . . What I want to know is upon your reading of that claim after you have read the patent is it interpreted by you to include within its scope both rigid and flexible vanes, or just rigid vanes?

A.   Well, I guess theoretically you could interpret it to include both.  However, it would not lead me to apply flexible vanes to this patent.

60                               As is discussed later, the trial judge rejected Mr. Mellinger as a person skilled in the art of “dual action” machines, and it may therefore be thought somewhat inconsistent for him to have accepted Mr. Mellinger as a skilled worker for the purpose of claims construction of a “dual action” patent.  However, in light of the fact that none of the experts called by any of the parties interpreted the patent as teaching the use of flex vanes, the expert evidence left it open to the trial judge to conclude that the '803 patent specification taught rigid vanes, and that the '803 claims should be so construed.

61                               The appellants object that the “vane” controversy ought to have been foreclosed by the Agreed Statement of Facts where the parties agreed that the appellants' flex vane machine infringed the '803 patent subject to the removable sleeve issue.  However, claims construction is a matter of law for the judge, and he was quite entitled to adopt a construction of the claims that differed from that put forward by the parties. 

62             The trial judge, explicitly relying on the evidence of the respondents' own expert, concluded that “an agitator with flex vanes, although not specifically excluded from the '803 patent, is, nevertheless, not included” (p. 171).  In other words, reading the claims with the knowledge and insight into the technical terms provided by the rest of the specification and by Mr. Mellinger's concession, he concluded that rigid vanes were essential to the '803 invention as claimed.  Although his analysis is flawed by taking the filing date rather than the date of issuance as the relevant time at which to construe the claims, his conclusion was based on the differences he perceived between unitary action and dual action, a difference that was as true on the date of issuance as it was on the date of filing.  In light of the expert evidence, it was open to him to construe the '803 claims accordingly.  The Federal Court of Appeal so held, and I agree.

3.               If the '803 Patent Claims Properly Construed do not Include Flex Vanes, is the '734 Patent Nevertheless Invalid Because of Double Patenting?

63                               The prohibition against double patenting relates back to the “evergreen” problem mentioned at the outset.  The inventor is only entitled to “a” patent for each invention:  Patent Act, s. 36(1) .  If a subsequent patent issues with identical claims, there is an improper extension of the monopoly.  It is clear that the prohibition against double patenting involves a comparison of the claims rather than the disclosure, because it is the claims that define the monopoly.  The question is how “identical” the claims must be in the subsequent patent to justify invalidation. 

64                               The Federal Court of Appeal has adopted the test that the claims must be “identical or conterminous”:  Beecham Canada Ltd. v. Procter & Gamble Co. (1982), 61 C.P.R. (2d) 1, at p. 22.  This verbal formulation derives from an editorial comment by Dr. H. G. Fox, Q.C., on Lovell Manufacturing Co. v. Beatty Bros. Ltd., reported at (1962), 23 Fox Pat. C. 112, at pp. 116-17:

Letters patent are not granted at pleasure, but for a term of years and the grant of a second patent with respect to the same subject-matter would be void under this statute [6 Henry VIII, c. 15, 1514] and by the Statute of Monopolies, as well as at common law and by the terms of section 28(1)(b) of the Canadian Patent Act.  But for this purpose the subject-matter of the two grants must be identical.  A subsequent claim cannot be invalidated on the ground of prior claiming unless the two claims are precisely conterminous.

65                               This branch of the prohibition on double patenting is sometimes called “same invention” double patenting.  Given the claims construction adopted by the trial judge it cannot be said that the subject matter of the '734 patent is the same or that the claims are “identical or conterminous” with those of the '803 patent.

66                               There is, however, a second branch of the prohibition which is sometimes called “obviousness” double patenting.  This is a more flexible and less literal test that prohibits the issuance of a second patent with claims that are not “patentably distinct” from those of the earlier patent.  In Commissioner of Patents v. Farbwerke Hoechst Aktiengesellschaft Vormals Meister Lucius & Bruning, [1964] S.C.R. 49, the issue was whether Farbwerke Hoechst could obtain a patent for a medicine that was a diluted version of a medicine for which it had already obtained a patent.  The claims were neither identical nor conterminous.  Judson J. nevertheless held the subsequent patent to be invalid, explaining at p. 53:

A person is entitled to a patent for a new, useful and inventive medicinal substance but to dilute that new substance once its medical uses are established does not result in further invention.  The diluted and undiluted substance are but two aspects of exactly the same invention.  In this case, the addition of an inert carrier, which is a common expedient to increase bulk, and so facilitate measurement and administration, is nothing more than dilution and does not result in a further invention over and above that of the medicinal itself.  [Emphasis added.]

67                               In Consolboard, supra, Dickson J. referred to Farbwerke Hoechst as “the main authority on double patenting” (p. 536) which stood for the proposition that a second patent could not be justified unless the claims exhibited “novelty or ingenuity” over the first patent:

Judson J. for the Court said that the second process involved no novelty or ingenuity, and hence the second patent was unwarranted.

68                               It is on this second branch of “obviousness” double patenting that the appellants rest their case against all of the claims of the '734 patent except the “continuous drive” claims which they concede to be valid albeit they contest infringement.

69                               The trial judge ruled that the subject matter of the '734 intermittent claims was the addition of flex vanes onto the dual action agitator.  There were other minor differences between the '734 patent and the '401 and '803 patents, specifically an option to have the vanes on the lower agitator slanted rather than vertical, and to have the upper agitator in a slope position rather than co-axial with the lower agitator.  Applying a purposive construction, however, these elements are clearly not “essential” because the '401 and '803 patents previously issued taught that the vanes could be vertical and the upper auger co-axial with the lower agitator, and the '734 patent claimed that flex vanes would work with these variants as well.  What distinguished '734 technology from '803 technology in respect of the intermittent drive claims was the substitution of flex vanes for rigid vanes, as the trial judge noted at pp. 189-90:  “[t]he essence of the invention is the unique wash system produced by the combination of flex vanes with dual action agitation”.

70                               The trial judge initially accepted the evidence of the appellants' expert, Mr. John Mellinger (whose testimony the trial judge found “enlightening and trustworthy” (p. 158)) that there would be no novelty in the use of flex vanes instead of rigid vanes but in the end rejected it because of Mr. Mellinger's lack of “dual action” experience.  The trial judge said (at pp. 178, 184-85 and 196):

The evidence of Mr. Mellinger is that, since Maytag's unitary action agitators with flex vanes were already on the market with commercial success, their use on the lower oscillating portion of a dual action agitator could not be considered a novel use.

                                                                   . . .

I must concede that, at first, I was convinced, on the basis of Maytag's positive experience with flex vanes, that it would have been obvious to appropriate Maytag's flex vanes for use on a dual action agitator.

                                                                   . . .

Mr. Mellinger admittedly had no experience with dual action agitators.  Mr. Pielemeier had a lot, and was involved in product development at the time of their invention.  Whose opinion evidence as to what the notional skilled technician would have thought about flex vanes on dual action agitators is to be preferred?  Why, Mr. Pielemeier's is, as he has the knowledge that would better support an opinion about dual action agitation.  Mr. Mellinger's opinion, though very interesting, clearly is not supported by knowledge about dual action agitation.

Mr. Pielemeier was an engineer who had been employed by the respondent Whirlpool Corporation for 15 to 20 years at the material time.  He had laboured in the respondent's product development department, and had “worked with the inventors of the patents before this Court” (trial judgment, at p. 158).  Someone with Mr. Pielemeier's connection to the respondents, burdened as he is with inside information, is not a very satisfactory proxy for the “ordinary worker”.  He is a skilled addressee but he is not operating on the basis of common knowledge in the trade.  The patent claims were not addressed by Whirlpool's research engineers to their colleagues in Whirlpool's product development group.  The patent claims were necessarily addressed to the wider world of individuals with ordinary skills in the technology of clothes washing machines.  As Aldous L.J. observed in Beloit Technologies Inc. v. Valmet Paper Machinery Inc., [1997] R.P.C. 489 (Eng. C.A.), at p. 494:

The notional skilled addressee is the ordinary man who may not have the advantages that some employees of large companies may have.  The information in a patent specification is addressed to such a man and must contain sufficient details for him to understand and apply the invention.  It will only lack an inventive step if it is obvious to such a man.  [Emphasis added.]

Dickson J. placed the same emphasis on “ordinariness” in Consolboard, supra, at p. 523:

The persons to whom the specification is addressed are “ordinary workmen”, ordinarily skilled in the art to which the invention relates and possessing the ordinary amount of knowledge incidental to that particular trade.  The true interpretation of the patent is to be arrived at by a consideration of what a competent workman reading the specification at its date would have understood it to have disclosed and claimed.

71                               “Ordinariness” will, of course, vary with the subject matter of the patent.  Rocket science patents may only be comprehensible to rocket scientists.  The problem with Mr. Pielemeier is that he could not be a good guide to the common knowledge of “ordinary workers” in the industry because his opinions were predicated on Whirlpool's in-house knowledge, and he made no bones about that fact.

72                               The appellants' expert, Mr. Mellinger, was unsatisfactory for quite a different reason.  He disclaimed any experience at all with “dual action” machines, and could not express an opinion on the differences or the similarities in design or operation in comparison to “unitary action” machines.  He had formidable qualifications as an expert in some areas but dual action machines was not among them.

73                               At the date the '734 patent issued (February 17, 1981), dual action machines no longer constituted esoteric technology intelligible only to the initiated.  Dual action machines had been public since June 1975 – almost six years prior to issuance of the '734 patent.  The '401 and '803 “dual action” patents had issued in Canada on January 2, 1979, and March 6, 1979, respectively, and in the United States considerably earlier than that.  They were not prior art opposable to the validity of the '734 patent because they were co-pending in the Canadian Patent Office, but by 1981 dual action machines and the earlier patents were nevertheless well known and available to those with “a practical interest in the subject matter of [the] invention” (Catnic, supra, at p. 242).  Although neither the '401 or '803 patent specifications disclosed Whirlpool's knowledge that dual action compounded tangling problems, they did explain how “dual action” works.  The trial judge accepted the evidence that the downward force of the upper auger complicated the washing machine environment by driving the clothes onto the oscillating vanes.  Workers of ordinary skill and knowledge had had six years of opportunity to reflect on the implications of downward force (dual action) versus no downward force (unitary action), but this was a subject to which Mr. Mellinger had apparently given little thought:

Q.   Are you familiar with any specific special types of tangling problems that happen in dual action agitation?

A.   Only having read that word and understanding – some of the art that I have read someplace talks about three-dimensional tangling.  I either heard it in testimony or read it in affidavits.  It's a new word I didn't know before I got involved with this case.

Q.   So it wasn't a problem that you were familiar with?

A.   I don't even know if it's a different problem from the ones that we were exposed to.  I don't know what it is.

Q.   As you sit here today and testify you're not in a position to tell the court whether you now know that there are any special tangling problems that come about because of dual action agitation?  You can't talk about that today?

A.   I can't talk about that without knowing, you know, the facts of what's out there. 

                                                                   . . .

Q.   You agreed with me yesterday that you had never exactly seen a rigid vane dual action agitator?

A.   That's correct.

74                               I think, as stated, the trial judge was wrong to have accepted the evidence of a long-time employee of the respondent Whirlpool Corporation as a proxy for the “ordinary worker”.  However, I also conclude that he was quite entitled to reject the evidence of Mr. Mellinger as not being a sufficient factual basis to invalidate the '734 intermittent drive claims.  The trial judge was concerned, as I read his opinion, that Mr. Mellinger's testimony was not supported by the level of practical understanding of dual action washing machines that by 1981 was common knowledge among the skilled workers who were interested in this end of the washing machine business.  Dual action agitators were, after all, big news for these people in the late 1970s.  While the hypothetical “ordinary worker” is deemed to be uninventive as part of his fictional personality, he or she is thought to be reasonably diligent in keeping up with advances in the field to which the patent relates.  The “common knowledge” of skilled workers undergoes continuous evolution and growth.  The trial judge made a finding of fact that it would be unsafe to rely on Mr. Mellinger's evidence because he had failed to keep up to date in this respect.

75                               Section 45  of the Patent Act  creates a presumption of validity.  The burden was on the appellants to prove on a balance of probabilities, that the patent was invalid.  The trial judge simply concluded that he had not been given sufficient proof to displace the presumption.  The Federal Court of Appeal agreed, and I see no basis on which this Court could properly interfere with these concurrent factual findings.

4.  Infringement of the “Continuous Drive” Claims

76                               The issue of infringement is a mixed question of fact and law.  Claims construction is a matter of law.  Whether the defendant's activities fall within the scope of the monopoly thus defined is a question of fact:  Western Electric, supra.

77                               With respect to claims construction, the continuous drive concept disclosed in claims 6, 8 and 14 of the '734 patent is not something that is found in either of the '401 or '803 patents.  The validity of the '734 patent in that respect is not in doubt.  The “continuous drive claims” read as follows:

6.  An agitator assembly as defined in claim 1, wherein said drive means is constructed and arranged to continuously drive said second agitator element.

                                                                   . . .

8.  The invention set forth in claim 7 wherein said drive means includes a drive member which is directly connected to said upper agitator element and constructed and arranged such that said upper agitator element is continuously rotated in one direction on said vertical axis during washing of fabrics.

                                                                   . . .

14. . . . the improvement of . . . a continuous, unidirectional driving means for continuously rotating said auger portion during a washing operation.  [Emphasis added.]

78                               The trial judge held that the intermittent claims and the continuous claims “are neither inclusive nor exclusive of each other” (pp. 175-76).  He said they included (at p. 176):

. . . a “continuously intermittent” motion, where during the operation of the machine, the motion of the upper auger may continuously be driven or rotated in intermittent pauses or spurts.  . . . As long as the movement is not sporadic, it may very well have been contemplated to fall within the scope of the claims of the invention”.

79                               This cannot be correct.  The claims clearly differentiate between two modes of operation.  Claims 5 and 6 are identical except that the former speaks of intermittent drive and the latter of continuous drive.  If the two claims are identical in other respects, one infers on a purposive construction that the claims were intended to describe alternative drive systems.  It is well understood that “[w]here one claim differs from another in only a single feature it is difficult to argue that the different feature has not been made essential to the claim”:  Hayhurst, supra, at p. 198; see also Jamb Sets Ltd. v. Carlton (1963), 42 C.P.R. 65 (Ex. Ct.), at p. 73, aff'd (1965), 46 C.P.R. 192 (S.C.C.); and Submarine Signal Co. v. Henry Hughes & Son, Ld. (1931), 49 R.P.C. 149 (Eng. C.A.), at p. 174.  The only difference between claims 5 and 6 is that claim 6 replaces the word “intermittently” with “continuously”.  Clearly, claims 6, 8 and 14 specify that for an intermittent drive means, there is substituted a drive means that continuously rotates the auger.  While it is true, as the trial judge observed, that for the patent as a whole “both intermittent and continuous drive means are envisaged” (p. 176 (emphasis added)), claims 6, 8 and 14 clearly specify a continuous drive and therefore will only be infringed by a machine that continuously drives the auger.  The trial judge essentially found infringement of the continuous claims by conflating them to encompass the intermittent claims.

80                               Moreover, contrary to the respondents' submission, the claims seem clearly to require some structural component.  Claims 6, 8 and 14 each refer to “drive means”.  In claim 6 it is to continuously drive the auger.  In claim 8 it is to be directly connected to the auger with the result that the auger is continuously rotated.  Claim 14 speaks of a driving means for continuously rotating the auger.

81                               The Federal Court of Appeal construed claims 6, 8 and 14 to require a continuous rather than intermittent drive means and I agree that, as a matter of law, this is the correct construction of those claims.

82                               The evidence of infringement is not very satisfactory.  The appellants declined to call a witness to describe the drive means utilized in their accused machines, preferring to sit back and argue that the respondents had not made sufficient proof.  Whatever evidence of the mechanics of the appellants' system was obtained during pre-trial discovery was apparently inconclusive.  The trial judge based his opinion on a video showing a rotating General Electric auger under a “'medium or light' wash load”.

83                               The respondents' infringement argument seems to come down to this.  Wash tub augers do not rotate unless they are driven.  If the GE auger is seen to rotate continuously, we can infer that it is connected to a drive means capable of continuously rotating it.  Appellants' counsel suggested that perhaps the tub water was turning the auger but one would have expected, on the contrary, that the backwash generated by the lower oscillating vanes would have created intermittent water resistance to such continuous rotation. 

84                               The appellants' reliance on the onus of proof, while perhaps sound tactics, left the court in an awkward position.  The respondents' evidence of infringement, while thin, was put into the balance against no evidence at all.  The Federal Court of Appeal concluded that the videotaped evidence supported the inference of continuous drive as well as the observed continuous rotation.  I conclude that in the absence of any GE evidence to the contrary, it was open to that court to use that inference to find, as a fact, infringement of the continuous drive claim.

85                               The appellants object that the factual finding of the Federal Court of Appeal in this respect differed from that of the trial judge, who, as stated, had erroneously construed the claims as contemplating that “the upper auger may continuously be driven or rotated in intermittent pauses or spurts . . . [a]s long as the movement is not sporadic” (p. 176), and found in the video that “[a]t times [the movement] appears continuous; at times intermittent” (p. 175).  The Federal Court of Appeal, which correctly construed the claims as requiring continuous drive and/or rotation, viewed the same videotaped evidence and was satisfied that “the motion of the upper element of the appellants' product while working under medium and light load conditions was continuous . . . [and that] the motion shown on the exhibit speaks for itself” (pp. 141-42).  It was open to the Federal Court of Appeal to make this finding of fact because the trial judge had misconstrued the claim and therefore misdirected himself as to what he was looking for.  The appellants, having elected not to call any evidence on this issue, are not well placed to argue that the Federal Court of Appeal made a palpable error in reaching the factual conclusion that it did.         

V.  Disposition

86                               The appeal is therefore dismissed with costs to the respondents.

Appeal dismissed with costs.

Solicitors for the appellants:  Smart & Biggar, Ottawa; Dimock Stratton Clarizio, Toronto.

Solicitors for the respondents:  Barrigar & Moss, Toronto.