Burton Parsons Chemicals, Inc. v. Hewlett-Packard (Canada) Ltd., [1976] 1 SCR 555

Supreme Court of Canada

Burton Parsons Chemicals, Inc. v. Hewlett-Packard (Canada) Ltd., [1976] 1 S.C.R. 555

Date: 1974-12-19

Burton Parsons Chemicals, Inc. and Burton Parsons and Company of Canada, Limited (Plaintiffs) Appellants;

and

Hewlett-Packard (Canada) Ltd. and X-Ray and Radium Limited (Defendants) Respondents.

1974: November 6, 7 and 12; 1974: December 19.

Present: Laskin C.J. and Martland, Judson, Ritchie, Spence, Pigeon, Dickson, Beetz and de Grandpré JJ.

ON APPEAL FROM THE FEDERAL COURT OF APPEAL

Patents—Validity—Reissue—Conductive cream for skin contact electrodes not a medicine—Interpretation of specification and claims in light of knowledge of man skilled in the art—Patent Act, R.S.C. 1970, c. P-4, s. 36(1) and 41(1).

Appellants were reissued their patent for a conductive cream to be used in making electro-cardiograms and the like. The patented substance is composed of an aqueous emulsion containing sufficient highly ionizable salt to provide good electrical conductivity. An action to impeach the initial patent was instituted by defendants on the grounds that some claims were broad enough to include also colloid dispersions, the use of which for such purposes was anticipated in a prior patent issued to one Jensen. For this reason the petition for reissue admitted that the inventor had inadvertently failed to revise the claims and included the addition of product claims. Unknown to defendants, this application was allowed by the Commissioner of Patents. They then instituted these proceedings. Defendants contend that the patent was invalid and could not be reissued, that the petition for reissue contained untrue statements and that the product claims were invalidated by s. 41(1) of the Patent Act. The Federal Court of Appeal reversed the judgment rendered in the Trial Division which upheld the reissued patent, holding that the claims in issue included claims that would not work and were therefore invalid. Hence the appeal to this Court.

Held: The appeal should be allowed.

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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. The invention relates to a mixture of no fixed composition. The essential is to combine a highly ionizable salt with an aqueous emulsion. If the patent is to have a practical value, it must cover all the emulsions and salts which can yield the desirable result, excluding only such substances as are not compatible with normal human skin. The characteristics of suitable emulsions and of suitable salts are well known and the avoidance of unsuitable salts due to their known noxious properties is similarly nothing but the application of the proper knowledge to be expected from a man skilled in the art.

As for the content of the petition for reissue, what is important is that the good faith of the inventor is not challenged and it is not seriously disputed that the initial patent disclosed the same invention as the reissued patent.

As for the cream, it is not intended for medicine within the meaning of s. 41(1) of the Patent Act and no evidence to the contrary was submitted.

Minerals Separation North American Corporation v. Noranda Mines Ltd. (1952), 69 R.P.C. 81; Société des usines chimiques Rhône-Poulenc v. Jules R. Gilbert Ltd., [1968] S.C.R. 950; Aktiengesellschaft Vormals Meister Lucius & Bruning v. Commissioner of Patents, [1966] S.C.R. 604, distinguished. Commissioner of Patents v. Farbwerke Hoechst A.G., [1964] S.C.R. 49; Sandoz Patents Ltd. v. Gilcross Ltd. (1973), 8 C.P.R. (2d) 210; Northern Electric Co. Ltd. v. Photo Sound Corpn., [1936] S.C.R. 649; Tennessee Eastman v. Commissioner of Patents, [1974] S.C.R. 111, referred to.

APPEAL from a jugment of the Federal Court of Appeal[1] reversing a judgment of the Trial Division upholding a reissued patent. Appeal allowed.

D.J. Wright, Q.C., and D.N. Plumley, for the plaintiffs, appellants.

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D.F. Sim Q.C., and R.T. Hughes, for the defendants, respondents.

The judgment of the Court was delivered by

PIGEON J.—This appeal is from a judgment of the Federal Court of Appeal reversing a judgment of the Associate Chief Justice sitting in the Trial Division. The judgment at trial had allowed the action of the plaintiffs, appellants in this Court (“Burton Parsons”), upheld their reissued patent and found the defendants-respondents (“Hewlett-Packard”) liable for infringement.

The patent in suit is for a conductive cream to be used in making electro-cardiograms, electroencephalograms and the like, it also covers the process of making such a cream. For satisfactory readings, it is necessary to have a good electrical contact between the machine’s electrodes and the parts of the human body on which they are applied. To that end it is usually necessary to apply some conductive substance to the skin. Prior to the invention, most substances used had disagreeable characteristics. An abrasive pumice powder was generally incorporated into a kind of paste which was rubbed on the skin and also required cleansing after the readings were taken. The patented substance is composed of an aqueous emulsion containing suffucient highly ionizable salt to provide good electrical conductivity. In practical terms, this means about five per cent common salt. A buffer solution is generally used in making up the emulsion but is not essential. Infringement is no longer denied by Hewlett-Packard but the validity of the patent is disputed.

The judgment at trial dealt in great detail with all the grounds of attack and rejected every one of them. The majority in the Court of Appeal namely, Jackett C.J. and Thurlow J., came to the conclusion, as the latter worded it, “that the claims in issue include claims for the use of substances that will not work and are on that account invalid”. MacKay J., dissenting, said:

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Reading the specifications and claims together it is my view that the claims in issue are limited to an electrically conductive system:

1. for use in making electrocardiograms and electroencephalograms;

2. that are composed of an aqueous emulsion having a base of an anionic, cationic or non-ionic material with the addition of 1-10% of a highly ionizable salt and in respect of some of the claims with the addition of a buffer solution such as to produce a pH of between 4-8 and in some of the claims the addition of suitable inhibitors such as esters of para-hydroxy benzoic acid to prevent the growth of bacteria, moulds or yeast.

3. That the materials to be used are only such of those materials within the general classifications as will be compatible with normal human skin and can be readily applied and readily removed without any resulting conditions requiring cleansing.

I think that these limitations as to the use of the invention and the limitation as to the materials to be used are an answer to the appellants’ submission that among the classifications of the materials referred to there are some that would be dangerous to use on the human skin. The patent does not claim that any emulsion or any highly ionizable salt could be used.

…

In the present case the patentees in their specifications and claims do not say that any highly ionizable salt or any aqueous emulsions may be used. They specify or clearly infer that the persons skilled in the art are to select from the general classifications of materials only such of those materials as would be effective for the expressed purpose and use of the invention which limited the selection to only such of the materials in the classes named as would be compatible with the human skin and which could be readily applied and removed without any resulting condition requiring cleansing.

It is my view that the specifications and claims are sufficient to comply with the requirements of section 36(1) of the Patent Act and that a person skilled in the art would not be left in any doubt as to the materials, their proportions and their consistency that he should use in preparing the invention.

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In coming to a different conclusion, the Chief Justice said in a foot-note:

It is true that section 36(1) requires that the disclosure describe the invention so as to enable “any person skilled in the art or science” to make, construct, compound or use it. In this sense the specification is directed to a person skilled in the art. It does not, however, mean that the specification means what it would mean to a person skilled in the art or science. See Northern Electric Co. Ltd. et al. v. Photo Sound Corporation et al., [1936] S.C.R. 649, per Duff C.J., delivering the judgment of the Court, at pages 676 et seq. Note particularly that the expert witness (i.e., the person skilled in the art) can give evidence as to the state of the art at any time, as to the meaning of technical terms, as to whether in his opinion what is described in a specification “on a given hypothesis as to its meaning” can be carried into effect by a skilled worker, or as to what at a given time to him as skilled in the art, a given sentence “on any given hypothesis as to its meaning” would have taught or suggested to him, but he cannot give evidence as to what the specification means or as to what it means to him as a person skilled in the art.

I must, with respect disagree with the statement that s. 36 “does not mean that the specification means what it would mean to a person skilled in the art”. What Duff C.J. was dealing with in the passage referred to was not the construction of the specification but the evidence admissible in that connection. In his remarks which were just as clearly obiter as those of Lord Tomlin he was quoting from, he objected to the practice of allowing an expert to say what the specification means to him as an engineer or as a chemist, the idea being to restrict experts to the task of supplying information respecting the particular science involved and its terminology so that the judge trying the case might reach his own conclusion as to the meaning of the document. The practical value of those observations does not require to be considered in this case as it does not turn on technical objections to evidence.

Counsel for Hewlett-Packard did not deny that the specification was to be construed as addressed to a person skilled in the art, however, he contended that a distinction had to be made between the disclosure and the claims. With this submission I

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cannot agree. The claims are part of the specification, it “ends” with them under the Act. What must be ascertained is what the whole meant at the date of the patent to a person skilled in the art. In Minerals Separation North American Corporation v. Noranda Mines Ltd.[2], Lord Reid said (at p. 92):

This claim is attacked on several grounds. The first attack is directed against the phrase “an alkaline xanthate”. This phrase is crucial because, so far as this claim is concerned, the inventor only claims a monopoly if the process described is carried on with an alkaline xanthate: if it is carried on with a xanthate not alkaline there is no infringement of this claim. It is therefore necessary to consider what this phrase would have meant at the date of the patent to the notional addressee of the specification, a person skilled in the art of froth flotation. (Italics supplied).

In that case on which counsel for Hewlett-Packard like Jackett C.J. and Thurlow J. strongly relied, the claims were held void essentially for the following reasons (per Lord Reid at pp. 93 and 95):

Even if the difficulty arising from the use of the word alkaline were surmounted, there would still be other obstacles in the way of the Appellants. The alkali metal xanthates include those cellulose xanthates in which the metal is an alkali metal, e.g., potassium cellulose xanthate. As will appear when their Lordships come to deal with Claim 9 such a xanthate does not assist the process of froth flotation; on the contrary it hinders the process. So Claim 6 could only be valid if the latter part of the claim, beginning with the words “adapted to co-operate” could be read as excluding those alkali metal xanthates which do not assist the process, and if this method of limiting the scope of the claim were held to be legitimate in this case. As their Lordships have already decided that Claim 6 is invalid, it is unnecessary to deal with these further objections to it. But their Lordships think it right to add that on this matter formidable arguments were adduced by the Respondents…

But it was argued for the Appellants that the whole phrase “an organic radical such as an alkyl radical” is a

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single and indivisible technical expression and must be held to mean what a chemist would understand it to mean. If it appears from evidence that a word in a specification has acquired a technical meaning among persons to whom that specification is addressed, then that meaning will be given to that word and the same may apply to a whole phrase. But there is not, and there could hardly be, evidence that this whole phrase has acquired a technical meaning among chemists or metallurgists. The terms “organic radical” and “alkyl radical” have technical meanings but that is all. So the contruction of a phrase or sentence in which these terms occur is a matter for the Court after the meanings of these terms have been ascertained from evidence. For the reasons which have been given their Lordships hold that this phrase does not exclude the cellulose radical and therefore, even if it could be held to qualify the word “xanthate” in Claim 9, the claim would still be invalid for inutility…

One other ground for excluding the cellulose xanthates was urged at one stage in this case. It was said that for various practical reasons no person skilled in the art would ever attempt to use these xanthates for froth flotation, and therefore they could be disregarded. But Counsel before their Lordships did not attempt to maintain this argument. It is well settled that, where the scope of a claim includes some method which is useless, the claim cannot be saved by showing that no skilled person would ever try to use that method.

In the present case, the situation is quite different. There is really no evidence that any cream prepared according to the specification with an aqueous emulsion containing sufficient highly ionizable salt to provide good electrical conductivity will not work. During the trial Hewlett‑Packard suggested that some combinations were unworkable, but counsel had to admit in this Court that those suggestions were conclusively disproved. All he could fall back on are some answers by Burton Parsons’ independent expert witness, Dr. Shansky, especially the following:

Q. May I take it Dr. Shansky that among the hundreds of emulsifiable materials, strong highly ionizable salts and buffer solutions known and avail-

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able in 1957, there would be some that would not be compatible with the human skin?

A. I would imagine that would be true that there could be in amongst the many that would be available, that some would not be compatible.

Q. In fact you would expect from the many combinations that there would be some that would not be compatible?

A, Yes, I would expect that.

It will be noted that this evidence is not that there are combinations that will not work but that there are substances coming within the specification that cannot be used because they are toxic or otherwise incompatible with the normal human skin. Of course, no person skilled in the art would think of using such substances. In Shansky’s evidence one reads:

Q. And you indicated that this eliminates from consideration, salts which would produce unsightly stains or would otherwise be harmful or deleterious to the human skin. Again you get this because of your knowledge that this substance is to be applied to the skin and you would know that this is a desirable characteristic?

A. That is correct.

Jackett C.J. in effect excludes those considerations in the following way:

…reference must be made to the whole claim, which reads as follows:

17. An electrocardiograph cream for use with skin contact electrodes and compatible with normal skin, comprising a stable aqueous emulsion that is anionic, cationic or non-ionic and, containing sufficient highly ionizable salt to provide good electrical conductivity.

Reading this claim in the only way that I find it possible to read it, it is a claim that the inventor has invented a substance that is an invention because of its new and useful qualities as an electrocardiograph cream that is for use with skin contact electrodes and that is compatible with normal skin and the substances for which such claim is made is the substance that is defined by all the words after the word “comprising”. The word “comprising” separates the part of the claim that performs the “fencing” function from the part of the claim that indicates what the function of the invention is. If the words of promise in the first part of the claim can be taken to limit the ambit of the invention defined, the

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public can be, by that device, completely deprived of the protection to which it is entitled under section 36(2).

With respect, I cannot agree that Claim 17 is invalid because the words “compatible with normal skin” are found before “comprising” instead of after, so that it would be valid, it seems, if the words were rearranged as follows:

17. An electrocardiograph cream for use with skin contact electrodes comprising a stable aqueous emulsion that is anionic, cationic or non-ionic, containing sufficient highly ionizable salt to provide good electrical conductivity and compatible with normal skin.

In my view, the rights of patentees should not be defeated by such technicalities. 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. The man skilled in the art will just as well appreciate this necessity if the cream to be made is described as “compatible with normal skin” as if it is described as containing only ingredients compatible with normal skin. The situation here is completely unlike that in either the Minerals Separation case or in Société des usines chimiques Rhône-Poulenc v. Jules R. Gilbert Ltd.[3]. In those cases the object of the patent was some substances of a definite chemical composition: xanthates in the first, substituted diamines in the second. Unfortunately for the patentees, the claims covered at the same time some xanthates which would not yield the desirable result in one case, and, in the other, some isomers which would not be therapeutically valuable. This is what was held fatal to the validity of the patents.

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In the present case, the invention relates to a mixture and a process for making it. This mixture is of no fixed composition. A great many different substances can be used, hundreds if not thousands, said Shansky. The essential is to combine a highly ionizable salt with an aqueous emulsion. As a result of this combination, the wetting action of the emulsion on the skin makes it possible to use the salt in a low concentration (from one to ten per cent). If the patent is to have a practical value, it must cover all the emulsions and salts which can yield the desirable result namely, all “emulsions with the outer phase or the continuous phase being water” and all salts that are highly ionizable enough to carry an electric current with low resistivity on the skin excluding only such substances as are not compatible with normal human skin. The evidence makes-it clear that this was obvious to any person skilled in the art because the characteristics of suitable emulsions and of suitable salts were well known. Only the combination was new.

This is the distinguishing feature from the other cases in which the properties of xanthates in froth flotation and those of some substituted diamines as antihistamines were the object of the invention. The inutility of cellulose xanthate in Minerals Separation, as well as that of some isomers of tripelennamine in Rhône-Poulenc was not known to the prior art. This is totally unlike the undesirable properties of some highly ionizable salts which Hewlett-Packard listed as objectionable. Their noxious character was well known and no man skilled in the art would have thought of using them in making a cream for use with skin contact electrodes any more than any such worker would have needed to be told that in making such a cream, he had to use such proportions of liquid and of emulsified material as to obtain a suitable consistency.

Such applications of the art of a skilled person is to be put on the same footing as the addition of a

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pharmaceutically acceptable carrier to a drug when this is required for its proper administration. In Commissioner of Patents v. Farbwerke Hoechst A.G.[4], this Court held that this last step in the production of a drug in dosage form was not patentable because there is no invention involved in it. In my view, the avoidance of unsuitable salts due to their known noxious properties is similarly nothing but the application of the proper knowledge to be expected from a man skilled in the art. In Sandoz Patents Ltd. v. Gilcross Ltd.[5], we had no hesitation in upholding claims for “therapeutically tolerable salts” of thioridazine to be obtained by reacting “with a therapeutically acceptable acid”. I cannot think that the omission of the qualification “therapeutically acceptable” would have voided the patent and I will note that in the Rhône-Poulenc case this question was left open.

It is stressed in many cases that an inventor is free to make his claims as narrow as he sees fit in order to protect himself from the invalidity which will ensue if he makes them too broad. From a practical point of view, this freedom is really quite limited because if, in order to guard against possible invalidity, some area is left open between what is the invention as disclosed and what is covered by the claims, the patent may be just as worthless as if it was invalid. Everybody will be free to use the invention in the unfenced area. It does not seem to me that inventors are to be looked upon as Shylock claiming his pound of flesh. In the present case, there was admittedly a meritorious invention and Hewlett-Packard, after futile attempts to belittle its usefulness, brazenly appropriated it. It was in no way misled as to the true nature of the disclosure nor as to the proper methods of making a competing cream. The objections raised against the claims really are that, except those pertaining to some specific embodiments of the invention, the others are so framed as to cover every practical emdodiment, leaving to the man skilled in the art, the task of avoiding unsuitable materials in the

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making of the mixture, a task which any man skilled in the art ought to be able to perform without having to be told because any unsuitability depends on well known properties. No unexpected or generally unknown unsuitability was proved or even suggested, which makes this case quite unlike Minerals Separation or Rhône-Poulenc.

The above observations dispose of the objection that the claims are broader than the invention. It is therefore necessary to consider the other grounds of invalidity which the trial judge dismissed and the majority in appeal did not have to deal with. The first of these other objections is that the claims are ambiguous on account of the use of the term “highly ionizable salt” and of the word “comprising”. With respect to the first expression, the evidence is that there is no generally accepted dividing line between salts that are highly ionizable and those that are not. There might thus be a difference of opinion between competent chemists as to whether some salts are included in the description or not. Why one would want to use salts of questionable utility when there are hundreds if not thousands of unquestionable suitability available was not indicated. In my view, this is enough to dispose of the objection. Even less need be said with respect to “comprising”. It is a word very frequently used in patent claims. It is no vaguer than “includes”.

Another objection raised is as to the validity of the patent sued upon as a reissued patent. The action herein was instituted by Burton Parsons on June 7, 1967. However, Hewlett‑Packard had, on June 10, 1964, instituted another action to impeach Canadian patent No. 631,424 issued to Burton Parsons on November 21, 1961. One of the grounds of attack was that some claims were broad enough to include not only emulsions, but also colloid dispersions, the use of which for such purposes was anticipated in a prior patent issued to one Jensen. Under those circumstances, Burton

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Parsons, on August 16, 1965, made a petition for reissue stating those facts as well as admitting that, although the Jensen patent had been cited by the U.S. Patent Office, the inventor had inadvertently failed to revise the Canadian claims adequately. Other changes were also sought, especially the addition of product claims. Unknown to Hewlett-Packard, the application for reissue was allowed by the Commissioner of Patents and these proceedings were subsequently instituted.

The first ground of attack rests on the contention that an invalid patent cannot be reissued. This is based on the judgment of this Court in Farbwerke Hoechst Aktiengesellschaft Vormals Meister Lucius & Bruning v. Commissioner of Patents[6], in which Martland J. speaking for the Court said (at pp. 614-15) after referring to a U.S. Court of Appeal decision:

Two points should be noted in respect of this decision. The first is that in this case a reissue had been granted in respect of a patent which had been held to be invalid. As has been pointed out earlier, the American statute in terms permits the reissue of an invalid patent in certain specified circumstances. The Canadian Act, however, does not so provide. Section 50 deals only with a patent which is defective or inoperative. In my opinion it contemplates the existence of a valid patent which requires reissue in order to become fully effective and operative. In the present case, in so far as the substance tolbutamide is concerned, the patent for which reissue is sought has been held by this Court to be invalid.

It must be noted that those words were said in a case where the Commissioner of Patents had rejected the application for reissue after this Court had held the patent invalid. The appeal was from the judgment of the Exchequer Court affirming the decision of the Commissioner. The final conclusion (at p. 619) was that “there was ample justification for the exercise by the Commissioner

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under s. 50 of his discretion in the manner which he did.”

Counsel for Hewlett-Packard also relied on the judgment of this Court in Northern Electric Co. Ltd. v. Photo Sound Corpn.[7] in which a reissued patent was held invalid because it was found that the Commissioner had exceeded his authority in granting it. However, it should be noted that an important change was made in the law since the patent under consideration in that case was reissued. At that time, the section providing for reissue patents read:

24. Whenever any patent is deemed defective or inoperative by reason of insufficient description of specification, or by reason of the patentee claiming more than he had a right to claim as new,…

By the Patent Act of 1923 (s. 27) this had been changed to read as in s. 50 of the present act “claiming more or less”, but this change could not validate the reissue effected November 28, 1922. That this was the essential reason for the invalidity appears from the reasons given for the Court by Duff C.J. (at p. 652):

…it is to be observed that, while the section provides for relief where the patentee claims too much, there is no provision for relief where the patentee fails to claim something to which he may be entitled.

As to the contention that there was no “error” because whatever inadvertence or mistake happened was that of the patent attorneys, not that of the inventor himself, I can see no reason for such a restrictive construction of the Act. On applications for extension of time, relief from a default and the like, no court would listen to the objection that the delay or the neglect was that of the party’s attorney, not of the party himself. On the contrary, it is a basic rule in the exercise of judicial discretion in such matters that a party should not suffer a deprivation of his rights due to the error or neglect of his attorney. It cannot seriously be suggested that the omission to amend the Canadian patent application in the same way as the U.S. application so as to take care of the Jensen patent was

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deliberate and was not a clear mistake or inadvertence.

Concerning the allegation that there were untrue statements in the petition for reissue, the truth of the matter, in my view, is that there was nothing but a failure to give complete particulars of immaterial details. Whether the inventor learned of the Jensen patent before or after his Canada application was filed, whether his error was in not drawing it or in not revising it so as to exclude colloid dispersions, is of no consequence whatsoever. What is important is that the good faith of the inventor is not challenged and it is not seriously disputed that the initial patent disclosed the same invention as the reissued patent.

The last ground of attack concerns the validity of the product claims only. They are said to be invalidated by s. 41(1) as being for “substances prepared or produced by chemical processes and intended for food or medicine”. The trial judge held that Hewlett-Packard had failed to prove that the preparation was by chemical process. As to this, I am not free from doubt. It is quite true that this must be determined on the basis of the popular, not the scientific meaning, of “chemical process”. In this testimony, Shansky very aptly explained how little help can be obtained from scientists on that point when he said:

…It is the difference between physical and chemical reactions. It is controversial, it depends upon what your discipline is, some people say tearing paper is physical reaction, some say it’s a chemical reaction because hydrogen bonds are being broken, solubilization is a chemical reaction, it changes the material from one state to another state and in that sense it is chemical. (Underlining added).

The trial judge noted that the fact that the process involved only a mixing of the ingredients was not decisive. It depends on what goes on. I am

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not at all sure that the preparation of the cream in question is to be looked upon as analogous to the preparation of mayonnaise, also an emulsion, which preparation would not, I think, be looked upon as a chemical process in usual terms. But most of the substances mentioned in the patent herein as suitable for the preparation of a conductive cream are undoubtedly “chemicals” in the usual sense of this word, especially the emulsifying agents. The above‑quoted statement from Burton Parsons’ expert witness, Dr. Shansky, implies an admission that, from the point of view of a chemist at least, the emulsification process using an emulsifier involves the use of its chemical properties.

I do not find it necessary to reach a firm conclusion on this point because I agree with the trial judge’s finding that this cream is not “intended for medicine” within the meaning of s. 41. Cases on the meaning of this expression were recently reviewed in Tennessee Eastman v. Commissioner of Patents[8]. Substances intended for use in surgery were held to be included. I have no doubt that a conductive cream is apt to be used whenever electrodes are applied to the skin during surgery. However, there is nothing in the evidence which would justify the conclusion that such is the main or primary use of the product. It is clear that such is primarily and mainly for the taking of electrocardiograms in routine examinations, not necessarily or mainly in connection with the treatment of diseases. It is obviously a matter of some difficulty to draw the line between what is a medicine and what is only a product apt to be used in connection with medical treatments. In the present case, however, Hewlett-Packard had the burden of proving that the product was a medicine. The evidence has failed to convince the trial judge that such was the case and I see no reason to disturb his finding.

For all those reasons I would allow the appeal, set aside the judgment of the Appeal Division and

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restore the judgment at trial with costs in all courts against the respondents.

Appeal allowed with costs.

Solicitors for the plaintiffs, appellants: Ridout & Maybee, Toronto.

Solicitors for the defendants, respondents: Donald F. Sim, Toronto.