On June 30 2017 the Supreme Court delivered an important and highly anticipated decision in AstraZeneca Canada Inc v Apotex Inc (2017 SCC 36) by rejecting the so-called 'promise doctrine' and clarifying the requirement for patent utility in Canada. The unanimous decision represents an important victory for innovators seeking protection in Canada and is especially welcome in the highly litigated area of pharmaceutical patents.

The promise doctrine developed by the federal courts in recent years had become the yardstick against which utility was measured. This was a highly contentious issue, as it resulted in the invalidity of numerous pharmaceutical patents. The Supreme Court fully rejected the doctrine as "incongruent with both the words and the scheme of the Patent Act".


In the case under appeal, the court considered AstraZeneca's patent covering the compound esomeprazole in Nexium, AstraZeneca's successful proton pump inhibitor (PPI) drug that reduces gastric acid and treats maladies such as reflux esophagitis. The patent was found to be novel and unobvious at trial (2014 FC 638), but invalid for lack of utility.


Applying the promise doctrine, the trial judge identified two promises:

  • use as a PPI; and
  • "improved pharmacokinetic and metabolic properties which would give an improved therapeutic profile such as a lower degree of interindividual variation".

There was no dispute that the first utility was soundly predicted, but the second was held not to have been demonstrated or soundly predicted at the filing date. The Federal Court of Appeal upheld this decision (2015 FCA 158).

The Supreme Court's total rejection of the promise doctrine is clear. It held that the promise doctrine is:

  • "not the correct method of determining whether the utility requirement under s. 2 of the Patent Act is met";
  • "not good law"; and
  • "unsound".

The court found that the promise doctrine is excessively onerous in two ways:

  • it determines the standard of utility that is required of a patent by reference to the promises expressed in the patent; and
  • where there are multiple expressed promises of utility, it requires that all be fulfilled for a patent to be valid.

The court set out the correct approach, as follows:

"[49] …ultimately, every invention pertains to a single subject-matter, and any single use of that subject-matter that is demonstrated or soundly predicted by the filing date is sufficient to make an invention useful for the purposes of s. 2.

[53] Utility will differ based on the subject-matter of the invention as identified by claims construction. Thus, the scope of potentially acceptable uses to meet the s. 2 requirement is limited – not any use will do. By requiring the usefulness of the proposed invention to be related to the nature of the subject-matter, a proposed invention cannot be saved by an entirely unrelated use. It is not sufficient for a patentee seeking a patent for a machine to assert it is useful as a paperweight.

[54] To determine whether a patent discloses an invention with sufficient utility under s. 2, courts should undertake the following analysis. First, courts must identify the subject-matter of the invention as claimed in the patent. Second, courts must ask whether that subject-matter is useful — is it capable of a practical purpose (i.e. an actual result)?

[55] The Act does not prescribe the degree or quantum of usefulness required, or that every potential use be realized — a scintilla of utility will do. A single use related to the nature of the subject-matter is sufficient, and the utility must be established by either demonstration or sound prediction as of the filing date."

Applying the correct approach, the Supreme Court found that AstraZeneca's patent was valid. At trial, the judge had found the claimed subject matter (ie, the optically pure salts of the enantiomer of omeprazole) to be useful for a purpose, as a PPI to reduce the production of gastric acid. That use was sufficient utility to make the subject matter useful within the meaning of Section 2 of the Patent Act.

Accordingly, the Supreme Court allowed AstraZeneca's appeal.

For further information on this topic please contact Lynn Ing at Smart & Biggar/Fetherstonhaugh by telephone (+1 416 593 5514) or email ([email protected]). The Smart & Biggar/Fetherstonhaugh website can be accessed