Double Patenting: A Tale of Three Dates

Bristol-Myers Squibb Canada v. Apotex Inc., 2017 FC 296 (dasatinib/SPRYCEL™ - Justice Manson)

In Canada, double patenting can be a difficult hurdle to overcome; the claims of a later-issued patent must be "non-coterminous" and "patentably distinct" from the claims of a co-owned earlier-issued patent. There are no procedural mechanisms in place, such as terminal disclaimers, to remove double patenting issues. Double patenting can be found between parent and divisional applications, which share filing and expiry dates, and between applications that are not directly related, but claim similar subject matter.

Double patenting is often raised in litigation, and the relevant date for assessing double patenting has been the subject of much recent debate. The choice has generally come down to one of three dates: the priority date of the earlier-issued patent, the priority date of the later-issued patent and the publication date of the later-issued patent. Four recent decisions discussed below, all involving Eli Lilly's drug tadalafil (CIALIS™) and Canadian Patent Nos. 2,226,784 and 2,181,377, have done little to clarify the matter.

In Eli Lilly Canada Inc. v. Mylan Pharmaceuticals ULC, 2015 FC 17, Justice Montigny held that the relevant date for a double patenting assessment was the priority date of the earlier-issued patent. On appeal (Mylan Pharmaceuticals ULC v. Eli Lilly Canada Inc., 2016 FCA 119), the FCA found that any date after the priority date of the later-issued patent was inappropriate, thereby excluding the publication date of the later-issued patent from the question. However, the FCA explicitly did not make a decision between the priority dates of the earlier- and later-issued patents as it was not determinative in the matter.

In Eli Lilly Canada Inc. v. Apotex Inc., 2015 FC 875, Justice Gleason disagreed with Justice Montigny that the relevant date was the priority date of the earlier-issued patent but again, since it was not determinative, did not decide on the relevant date. On appeal (Apotex Inc. v. Eli Lilly Canada Inc., 2016 FCA 267), Apotex argued that the Supreme Court in Whirlpool Corp. v. Camco Inc., 2000 SCC 67, had found that the relevant date was the publication date of the later-issued patent and, therefore, the FCA decision in Mylan Pharmaceuticals ULC v. Eli Lilly Canada Inc., 2016 FCA 119, was inconsistent with the Supreme Court and should not be followed. This was discussed at length in the decision and it was held that the Supreme Court did not address the relevant date explicitly and certainly not with any binding authority. Once again, the FCA did not choose whether it is the priority date of the earlier-issued patent or that of the later-issued patent that is the relevant date in the double patenting analysis.

Now here, in Bristol-Myers Squibb Canada v. Apotex Inc., 2017 FC 296, Justice Manson has chosen the priority date of the later-issued patent as being the relevant date. Although the choice of dates actually affected the outcome in this case with respect to double patenting, the claims were held to be invalid for obviousness in any event. Thus, a strict determination on the relevant date for double patenting was not necessary. This decision has been appealed and it will be interesting to see if the FCA finally decides to put the question of the proper date for a double patenting analysis to rest.

As a curious aside, in this decision, Justice Manson stated that the relevant date for assessing both sufficiency and utility is the priority date of the patent in question (para. [54]). This, however, is contrary to established jurisprudence in Novartis Pharmaceuticals Canada Inc. v. Teva  Canada Limited, 2013 FC 283, which held that the relevant date for assessing sufficiency is the publication date of the patent, and in Aventis Pharma Inc. v. Apotex Inc., 2006 FCA 64, which held that the relevant date for assessing utility is the Canadian filing date.