Canada: Supreme Court Of Canada Rejects The Promise Of The Patent Doctrine

The Supreme Court of Canada released on June 30, 2017 its long-awaited decision1 (available here) addressing the issue of the "promise of the patent." The Promise Doctrine required patentees to establish arguable statements of utility in the patent disclosure or risk losing their patents. In its reasons, the Court confirmed what many patentees have been arguing for more than a decade – that the "excessively onerous" Promise Doctrine is unsound and not the correct method for determining whether an invention has sufficient utility under section 2 of the Patent Act.

In discarding this recent judicial construct, the Court focused on the requirements of the Patent Act and re-emphasized the centrality of the established patent doctrine of purposive claims construction. The Court provided guidance on how to correctly assess a claimed invention's utility and emphasized the low threshold for utility, namely a scintilla of utility. The Supreme Court thus refocused the utility requirement on its traditional purpose of preventing "patenting of fanciful, speculative or inoperable inventions" rather than invalidating patents for inventive, novel and otherwise useful inventions.

Applying this framework, the Court allowed AstraZeneca's appeal and found that its patent was valid, overturning both underlying Courts.


AstraZeneca sold esomeprazole (a proton pump inhibitor) in Canada as the commercially successful product Nexium®. AstraZeneca owned Canadian Patent 2,139,653, which claims a novel salt of this compound.

Apotex sought to market a generic copy of esomeprazole and thus sought to impeach the 653 Patent. Apotex alleged the patent was invalid for, among other things, inutility. The Trial Judge's utility analysis turned on its application of the Promise Doctrine to the following stray statement in the patent disclosure:

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. The present invention provides such compounds, which are novel salts of single enantiomers of omeprazole. (emphasis added by the Federal Court)

The Trial Judge concluded that this statement constituted a "promise of the patent" which is "fundamental to the utility analysis" as the "yardstick against which utility is measured".  While there was no dispute that AstraZeneca had demonstrated that the claimed compound was a useful PPI, the Trial Judge nonetheless found the patent invalid for lack of utility as AstraZeneca had not demonstrated or soundly predicted the promise of an improved profile as of the filing date. The Federal Court of Appeal adopted the Trial Judge's analysis and affirmed both the status and application of the Promise Doctrine.

The Promise Doctrine is unsound and inconsistent with the Patent Act

The Supreme Court began its analysis by pointing out an immediately apparent flaw with the Promise Doctrine. That is, issues of validity generally focus on the claims alone, turning only to disclosure if there is ambiguity in the claims. The Promise Doctrine, however, improperly directs courts to consider the disclosure to identify potential promises irrespective of any such ambiguity.

The Court then held that the Promise Doctrine runs counter to the scheme of the Patent Act by conflating two of its requirements. The Court distinguished the section 2 requirement that an invention be "useful" and the section 27(3) requirement to disclose an invention's "operation or use", noting that the Supreme Court previously sought to clarify this very confusion in an earlier seminal patent decision.2 The Court rejected the notion that the reference to a "promise" in an oft-cited passage in that decision referred to or embodied the Promise Doctrine. The Court thus found that the Promise Doctrine inappropriately imports the section 27(3) requirement into section 2 by requiring that any use disclosed in the patent be demonstrated or soundly predicted at the time of filing.

The Court also found the Promise Doctrine to be inconsistent with the Patent Act because it requires that multiple uses be established. However, section 2 of the Act requires only that the invention be "useful". Any single use that is demonstrated or soundly predicted by the filing date is sufficient. The Promise Doctrine, given that it risks depriving a useful invention of patent protection if even a single "promised" use is not established, was thus found to be punitive and have no basis in the Patent Act. The Court also added that its operation, which can invalidate a patent based on discrete unintentional overstatements of use, would discourage patentees from fully disclosing their inventions, contrary to the purpose of section 27(3).

The Correct Approach to Assessing Utility

The Court held a scintilla of utility is all that is needed (ie. the invention must not be devoid of utility) and that utility must be established by either demonstration or sound prediction as of the filing date. The utility in question will vary based on the subject-matter of the invention as identified by claims construction, and a single use related to the nature of that subject-matter is sufficient.

The Supreme Court thus provided a two-step framework for assessing a claimed invention's utility:

  1. Identify the subject-matter of the invention as claimed.
  2. Is that subject-matter useful, i.e. is it capable of a practical purpose? No degree or quantum of usefulness is required – a scintilla of utility of utility related to the nature of the subject-matter is sufficient.

The Court also clarified that a patentee is not required to disclose the utility of the invention to fulfill the requirements of s. 2 of the Patent Act.


As regards the Promise Doctrine, the Supreme Court's momentous decision thus brings Canadian patent law back in line with the rest of the world. It will no doubt be a welcome development for innovators, providing more certainty for patents which had increasingly been challenged on the basis of subjective patent interpretations and often malleable and evolving requirements.


1 AstraZeneca Canada Inc. v. Apotex Inc., 2017 SCC 36

2 Consolboard Inc. v. MacMillan Bloedel (Sask.) Ltd., [1981] 1 S.C.R. 504.

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.

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