Under the Patent Act, an invention must be useful to be patentable. While in Canada the inventor does not need to describe the utility of the invention in the patent, where the patent makes a promise of utility, utility is measured against that promise. If the inventor does not make an explicit promise of a specific result, the threshold to find utility will be low; a “mere scintilla” of utility will suffice. Under the “promise doctrine”, a patent which would otherwise be valid can be invalid if it promises more than the invention delivers.
As a result, discerning whether the specification has a promise of a specific result can have significant impact on the validity of a patent. The recent Federal Court of Appeal decision of Apotex Inc v Sanofi-Aventis Canada Inc (“Sanofi”), for which the Supreme Court has granted leave to appeal, advocates for a degree of constraint when determining whether a patent contains a promise.