In Canada, valid patents must have “utility” – a similar concept to “industrial application”, as required in European patent applications. However, in some cases, utility cannot be fully verified by tests at the time of filing the patent application. In these instances, utility must be soundly predicted.

In Sanofi-Aventis v Apotex (2013 FCA 186), the Federal Court of Appeal (FCA) confirmed and updated the “promise of a patent” doctrine by qualifying that such a promise must be explicit within the patent application (as outlined in our previous article).

This doctrine has been subsequently developed by the FCA, such as in the 2015 decision relating to AstraZeneca’s Canadian Patent 2,139,653 for esomeprazole (NEXIUM) (AstraZeneca Canada v Apotex [2015 FCA 158]), in which the FCA found the patent to be invalid for lack of utility because it failed to meet at least one promise identified by the court in the application’s description. These subsequent decisions shed light on what is considered an explicit promise.

The Federal Court has clarified that there is a difference between a promise and a goal. Differentiating between goals and promises is a question of characterisation. Goals merely describe potential uses of the invention. Promises are explicit and define guaranteed or anticipated results from the patent.

Insofar as the NEXIUM patent was concerned, the Court was of the opinion that the particular patent promised an improved therapeutic profile. This interpretation was based on the ordinary meaning of the auxiliary verb “will” in a passage of the description. The courts were not convinced that the verb could be read as indicative of a goal of the invention, but rather considered the verb to amount to a promise.

Hence, while the FCA previously interpreted the utility requirement that a claimed invention be “new and useful” to mean that it has practical utility as opposed to theoretical utility, the post-2013 FCA decisions indicate that special attention should be paid to avoid any wording in the description that may be read as a promise.

As the Supreme Court of Canada said 35 years ago, an inventor must say what it is they claim to have invented, but are not obliged to extol the effect or advantage of their discovery, if they describe their invention so as to produce it.