2,366,932 / 2,519,898 / dasatinib / SPRYCEL / NOC
Patent law has a reputation of being an arcane and technical area of law. To me, it doesn’t generally seem that much worse than, say, corporate law, or even administrative law (where as soon as everyone figures out what the law is, the SCC changes it). But double patenting definitely lives up to the billing of being both arcane and technical. Manson J’s Dasatinib decision is significant in holding that the appropriate date for assessing obviousness-type double-patenting is the claim date of the second patent, in a case in which it actually mattered on the facts. However, the holding was not strictly necessary to the result, as the claims in question were invalid under a standard obviousness analysis, and Manson J’s reasons for selecting that date were brief. On the whole, the question of whether the claim date of the first or second patent is appropriate, remains open.
Obviousness-type double patenting is a judicially created doctrine which prevents an inventor from obtaining a second patent for an invention which is an obvious variant of an invention disclosed in its own prior unpublished prior application, even though that prior application is not part of the state of the art defined in s 28.3. The problem arises when the first patent is published after the claim date of the second patent (because otherwise it will typically be prior art in any event). The problem has normally been framed as involving a choice between three possible dates (from earliest to latest) (see Mylan FCA 2016 FCA 119, ):
(1) the claim date of the first patent (First Claim date);
(2) the claim date of the second patent (Second Claim date);
(3) the publication date of the second patent (Second Publication date):
The question is important only when the state of the art has changed in the interim. Keep in mind that when we are considering the correct date for assessing double patenting, it must already have been established that the double patenting doctrine applies, and so it is established that the first patent is considered to be part of the state of the art against the second, regardless of what date is used.
Recently, the law has been developed primarily in the context of NOC litigation dealing with two patents related to tadalafil, the earlier 377 patent, and the later 784 patent. In Mylan FC 2015 FC 17, discussed here, de Montigny J held that the appropriate date was (1), the First Claim date. Then, in Apotex Tadalafil FC, dealing with the same two patents, Gleason J expressed a preference for (2), the Second Claim date, but on the facts it was not necessary for her to decide between the First and Second claim dates: see here. The next decision, chronologically, was Mylan FCA, the appeal from Mylan FC. As discussed here, the Rennie JA, speaking for the FCA, definitively ruled out (3), the Second Publication date, but held that it was an open question as to whether the First or Second Claim date was correct. This effectively over-ruled de Montigny J’s holding that (1), the First Claim date, was appropriate, though he was affirmed in the result, because on the facts the result was the same whether the First or Second Claim date was used. Then, in Apotex Tadalafil FCA, Apotex argued that Whirlpool 2000 SCC 67 had held that (3), Second Publication date, was correct. The FCA rejected that argument and encouraged some out-of-the-box thinking: see here. Thus, coming in to this case, we have a clear holding from the FCA eliminating (3), the Second Publication date, but otherwise an entirely open question as between (1) and (2), the First or Second Claim date.
In this case, Manson J held that (2), the Second Claim date, is the correct date. This mattered on the facts, because Manson J held the claim at issue to be obvious as a consequence, but if the First Claim date, was used, the claim at issue would not have been obvious . With that said, he had already held that claim to be obvious on a traditional obviousness analysis .
I must say that I find Manson J’s reasoning on this issue more difficult to follow that the rest of his decision. He said that in Apotex Tadalafil FCA the FCA had
declined to affirm Justice Rennie’s exclusion of the Second Publication date (Apotex Tadalafil FCA at para 41). Therefore, the law as it currently exists on the appropriate date for the obviousness-type double patenting analysis is inconclusive. 
I find this passage confusing. It might be read as suggesting that Apotex Tadalafil FCA had doubted Rennie JA’s holding and re-opened the Second Publication date as a possibility, but I can’t read the decision that way. Apotex’s argument in Apotex Tadalafil FCA was Mylan FCA was wrongly decided because it was inconsistent with Whirlpool. This FCA rejected the inconsistency argument, and that is why Pelletier JA said “there is no reason for us to depart from Mylan FCA” ; he was not suggesting that Mylan FCA was doubtful authority and might be reconsidered.
Manson J then went on to say that he found the policy arguments made by Apotex for using Second Publication date to be persuasive in principle , . However, those arguments were only briefly described, as being to the effect that the evil of double patenting “is to force the public to endure a prolonged monopoly on an invention,” and the publication date of the second patent “is the first date at which the patentee can enforce the second patent and the public is threatened by the risk of liability for infringement” . I must say that I don’t see the force in this at all. An inventor is entitled to an invention which is not obvious as of the claim date, so the monopoly is “prolonged” only if the patent was obvious as of the claim date. Many valid patents are granted for inventions which would be obvious as of their publication date. And while the point about enforcement and liability is more or less true (though strictly, the patentee can’t enforce the patent until it is granted), I don’t really see the relevance. Manson J made the point only briefly, and no doubt it was clearer from the submissions.
No doubt Manson J’s discussion of the policy arguments was so cursory because he then went on to say, albeit in a roundabout way, that he was in any event bound by Mylan FCA to reject the Second Publication date . Then, quoting a passage from Apotex Tadalafil FC  in which Gleason J said that “a sound argument” could be made for using (2), the Second Claim date, Manson J held that the Second Claim date, or more specifically, the Second Priority date, was indeed the correct date . As discussed here, while Gleason J made a number of good points in her careful analysis, she did not definitively come down in favour of the Second Claim date. (I note that Manson J referred to the “Second Priority date,” while I have been referring to the “Second Claim date.” As discussed here, I think it is implicit in the decisions that it is reallythe choice between the earlier or later claim date that is at issue, even though in most of the cases this has been the priority date.)
In summary, Manson J’s Dasatinib decision is significant in holding that the appropriate date for assessing obviousness-type double-patenting is the Second Claim date, in a case in which it actually mattered on the facts. However, the holding was not strictly necessary to the result, as the claims in question were invalid under a standard obviousness analysis. Moreover, Manson J’s decision was thinly reasoned on this point. Given that Gleason J in Apotex Tadalafil FC did not feel bound to follow the much more thoroughly reasoned decision of de Montigny J in Mylan FC, I would say that it remains an open question as to whether the First or Second Claim date is appropriate.