As Napoleon once said, “The best way to keep one’s word is not to give it.” This is especially true for patents, where making a promise that an invention will do something may have very important consequences.

On March 10, 2016, the Supreme Court of Canada granted leave to AstraZeneca to appeal the Federal Court of Appeal’s decision in AstraZeneca Canada Inc. v. Apotex Inc., 2015 FCA 158. The Federal Court of Appeal had earlier dismissed AstraZeneca’s appeal from a decision of the Federal Court that invalidated its patent for lack of utility in the course of infringement proceedings. The patent was for the compound esomeprazole, also known as Nexium (for reducing gastric acid and reflux esophagitis).

One of the main issues before the Federal Court was whether the patent had made an explicit promise regarding the claimed compound. Under current jurisprudence, if a patent makes a promise, the patent will be considered to have utility only if that promise is fulfilled. On the other hand, if the patent does not make any promises, then the patent only needs to show a “mere scintilla” of utility.

At trial, the interpretation of the following sentence from the patent’s description proved to be key:

“It is desirable to obtain compounds with improved pharmacokinetic and metabolic properties which will give an improved therapeutic profile such as a lower degree of interindividual variation.” [underlining added]

AstraZeneca had argued that the word “will” merely expressed a hoped-for goal, and not an explicit promise. However, the Federal Court found that the ordinary meaning of the word “will” conveyed a sense of probable or certain outcomes, rather than potential outcomes. In contrast, words such as “may” or “could” would not convey that same sense. As a result, the Federal Court determined that the patent did promise an improved therapeutic profile (such as a lower degree of interindividual variation). The Federal Court went on to find that this promise was not demonstrated (or soundly predicted), meaning that the patent was invalid.

 The Federal Court of Appeal found no error in the analysis conducted by the Federal Court and unanimously upheld the decision. In particular, the Federal Court of Appeal found that the Federal Court was entitled to look at the disclosure as a whole (including the sentence quoted above) in assessing whether a promise had been made.

The Supreme Court of Canada will now have the opportunity to weigh in on this issue (and possibly other issues, since the Supreme Court of Canada, as usual, did not provide reasons for granting leave). The question of the role (if any) that “promises” play in a patent has been controversial and is currently the subject of a challenge by Eli Lilly against Canada under the North American Free Trade Agreement. In it, Eli Lilly has argued that the Federal Courts’ jurisprudence in this area has, in effect, run amok.

Regardless of how the Supreme Court of Canada rules, it is somewhat sobering to consider the possible impact of a single word in the description on the ultimate validity of the patent. Conceivably, if the word “may” had been used in the sentence instead of the word “will”, this entire issue could have been avoided.