The Federal Court of Appeal has provided guidance on the law of obviousness-type double patenting in dismissing Mylan’s appeal pertaining to Eli Lilly’s Canadian Patent 2,226,784, covering Lilly’s drug Cialis® (tadalafil).1 The FCA’s decision affirmed the result set out in de Montigny J.’s (as he then was) decision of January 7, 2015 (the “Trial Decision”)2 in which Mylan’s allegations of lack of utility and obviousness-type double patenting were rejected.

Obviousness-Type Double Patenting

Rennie JA, writing for the unanimous panel, discussed three legal issues with respect to obviousness-type double patenting. First, obviousness-type double patenting was distinguished from traditional “obviousness” attacks brought pursuant to section 28.3 of the Patent Act. The FCA held that “obviousness” per se is directed at whether there is an “invention” at all, whereas obviousness-type double patenting looks at whether an otherwise valid patent is simply “an extension of the patent that has already been granted”.3 The FCA held that only the earlier patent can be cited against the patent at issue in considering obviousness-type double patenting (rather than a mosaic of documents in a traditional obviousness attack), but that obviousness-type double patenting allows for the prior patent to fall within the one-year grace period provided by s. 28.3(a) for prior disclosures by the patentee and still be citable against the patent at issue.4

Second, the FCA further distinguished obviousness-type double patenting from traditional obviousness by noting that the former requires a comparison of the claims of the two patents, whereas traditional obviousness takes into account the entire art in the field of the invention that would have been known to a person skilled in the art as of the relevant time. The correct evaluation considers the claims as construed, and does not involve a comparison of the inventive concepts of the two claims.5

Finally, the FCA considered the relevant date for considering obviousness-type double patenting. Three options were presented: the claim date of the first patent, the claim date of the second patent, and the publication date of the second patent. The choice of date was critical, with Mylan likely to be successful if the second patent’s publication date was chosen, and Lilly successful otherwise. Mylan would have succeeded if the publication date of the second patent were chosen as, by this date, the skilled person’s common general knowledge had advanced such that the claims of the two patents would not have been considered to be patentably distinct to a skilled person.

The FCA held that the publication date of the second patent is not the relevant date, holding that it would be “inappropriate” to use any date later than the claim date of the second patent. The FCA reasoned that choosing the later date would “mean that a court assessing an obviousness-type double-patenting claim would consider prior art beyond what section 28.3 allows the Court to consider when assessing classical obviousness”. They held that such a circumvention of the section 28.3 dates is only permissible when considering the patentee’s own previous documents as a guard against evergreening, but that there was no equivalent reason to allow a challenger to circumvent the Patent Act with respect to any other prior art. As rejecting this date was dispositive, the FCA did not consider the further question of whether the appropriate date is the claim date of the first or second patent (or some other date, such as possibly the publication date of the first patent).6 The FCA may revisit this issue when it considers the appeal of Apotex on the same patent (scheduled to be heard May 5, 2016, A-330-15).


The FCA also briefly considered utility with respect to one dependent claim, claim 18, finding that its utility was soundly predicted. The FCA noted that the issue was obiter because the other claims of the 784 Patent survived the double-patenting attack, and thus even if this sole dependent claim fell this would not have changed the outcome of the case.7