Justice Rothstein notes that Backman limits to a certain extent the use of foreign law in Canadian tax cases

Observations of Marshall Rothstein, who retired from the bench on August 31, 2015, on practices in the Supreme Court of Canada include:

• “The Supreme Court has indicated a willingness to depart from its own precedent where a new legal issue has been raised or where there has been a change in the facts that ‘fundamentally shifts the parameters of the debate.’”
• Signing of judgments by “The Court” as “a rule of thumb..is reserved for controversial cases of significant public importance” (e.g., assisted dying, medicinal pot).
• On rare occasions, the Court will order oral argument on leave applications, as was done in Daishowa-Marubeni, where counsel were told they were to focus on two specific issues.
• Reasons for considering foreign judgments in Treaty interpretation cases include looking to “the effects of a particular rule in action in considering the merit of arguments about likely consequences.”
• In Backman:

The Court wrote that if a partnership wants to deduct losses under Canadian law, it must satisfy the elements of a partnership under Canadian law. This precedent limits to a certain extent the use of foreign law in Canadian tax cases.

• “The judges...will not engage in blogging” [or other disreputable conduct].

Neal Armstrong. Summaries of Justice Marshall Rothstein, "An Overview of the Supreme Court of Canada," Bulletin for International Taxation (IBFD), January/February 2016, p. 20 under General Concepts – Stare decisis, Supreme Court Act, s. 40(1), Treaties – General, s. 96, s. 247(2) and s. 248(10).