Lawyers, patent &
trademark agents

Supreme Court Rejects 'Promise of the Patent' Doctrine

On June 30, 2017, the Supreme Court of Canada released a seminal decision in Canadian patent law. Its decision in AstraZeneca Canada Inc. v. Apotex Inc., struck down the controversial “promise of the patent” utility doctrine that has made it more difficult to secure valid patent protection in Canada over the last 10 years. As we previously reported, the development of this doctrine by our courts took Canada out of step with other major countries and many argued that it was contrary to Canada’s treaty obligations which are intended to harmonize international requirements for patentability.  

Utility – Definition

Section 2 of the Patent Act requires the subject-matter of an invention to be useful, but it does not specify a standard for determining whether this utility exists.  Historically, the threshold for utility was thought to be very low: a mere scintilla of utility.  What mattered was that the invention could carry out some useful objective, was not merely a laboratory curiosity and was not something fanciful, speculative or inoperable.

Disclosure Obligation

Section 27(3) of the Patent Act requires the patent to provide a full disclosure of the invention to enable the skilled person to use or construct it after the patent expires. This is a critical element of the patent system which is based on the so-called “patent bargain” in which the inventor is granted exclusive rights in their invention for a limited period in exchange for disclosure of the invention so that society can benefit from this knowledge.

Promise of the Patent Doctrine

In recent years, the Federal Court has considered several cases involving challenges to the validity of patents issued in the highly competitive and very crowded pharmaceutical field. Patents in this field are often quite narrow in scope and relate to improvements to or modified formulations of known compounds. Patents may contain statements explaining what the inventors hope to achieve or what could set the inventions apart from what has gone before. The Courts began to look at these statements as a yardstick against which to measure whether an invention has utility.

The Federal Court of Appeal expressed the Promise Doctrine this way:

Where the specification does not promise a specific result, no particular level of utility is required:  a “mere scintilla” of utility will suffice. However, where the specification sets out an explicit “promise”, utility will be measured against that promise. The question is whether the invention does what the patent promises it will do. (Eli Lilly Canada Inc. v. Novopharm Ltd. 2010 FCA 197.)

The Promise Doctrine requires: (1) the identification of promises based upon a review of the entire specification for the patent; and (2) a determination of whether the applicant has demonstrated that it fulfilled all the promises set out therein.

AstraZeneca Canada Inc. v Apotex Inc.

AstraZeneca Canada sued Apotex Inc. for infringement of its Canadian Patent No. 2,139,653 (the ‘653 patent) for the drug esomeprazole (NEXIUM®), a proton pump inhibitor used to reduce gastric acid production in the treatment of a variety of gastrointestinal disorders. At trial, the Federal Court held the ‘653 patent to be invalid because it lacked utility. In reaching that conclusion the court applied the Promise Doctrine to conduct its analysis. The court reviewed the entire patent specification, including both the description of the invention and the claims that define the monopoly granted by the patent. In this review, it identified two promises, namely: (1) esomeprazole is effective as a proton pump inhibitor; (2) it has improved therapeutic and metabolic properties. The court found that the first promise was satisfied, but that the second promise was not demonstrated or soundly predicted when the patent application was filed. The Court took the position that the second promise extended to all the claims granted by the patent meaning that the entire patent was invalid. At the Federal Court of Appeal, the trial decision was upheld and AstraZeneca Canada appealed further to the Supreme Court of Canada.

Issue for Supreme Court

The main issue before the Supreme Court was whether the Promise Doctrine was the correct standard of utility under the Patent Act in Canada.  

The Supreme Court found the Promise Doctrine to be incongruent with the language and scheme of the Patent Act.  By considering statements in the patent specification outside the claims as part of the utility analysis, the promise doctrine "effectively imports s.27(3) into s. 2 inappropriately by requiring … any disclosure of use to be demonstrated or soundly predicted at the time of filing. If that is not done successfully, the entire patent is invalid as a precondition for patentability—an invention under s. 2 of the Act—has not been fulfilled". The Promise Doctrine changes the threshold issue of utility into a rigorous analysis of the sufficiency of the invention disclosure. This is particularly onerous if a person finds that there are multiple "promises", but only some of them have been fulfilled. Further, the effect of the Promise Doctrine was to undermine the disclosure requirement by discouraging fulsome disclosure for risk of invalidity on the basis of "an unintentional overstatement of even a single use".

The Supreme Court confirmed that the proper analysis under Section 2 is to identify the subject matter of the invention as it is defined by the claims granted by the patent and then ask whether that subject matter is useful—capable of a practical purpose or an actual result. This is a threshold issue which goes to whether the invention is eligible to even be considered for patent protection. A mere scintilla of utility will do, as the Patent Act does not prescribe any degree or quantum of usefulness to be required. A single use related to the nature of the subject-matter is sufficient.

Once this threshold issue is determined, then it is necessary to determine whether the patent is valid applying other criteria, including whether: (a) the subject matter is novel; (b) the subject matter is inventive; and (c) the patent provides a full disclosure of the invention to enable the skilled person to use or construct it after the patent expires per section 27(3).   


The Supreme Court’s clear statement that the Promise Doctrine is not good law brings the law on patent utility in Canada back into step with international patent standards. Canada’s utility standard once again reflects a low threshold which is comparable to the standards applied by other countries that are signatories to the NAFTA and TRIPS agreements.