Burden of Proving Priority

Hospira Healthcare Corporation v. Kennedy Trust for Rheumatology Research 2020 FCA 30 Locke JA: Rivoalen, Nadon JJA var’g 2018 FC 259 Phelan J
            2,261,630 / infliximab / INFLECTRA

An apparently novel issue raised in this appeal was the burden of proving priority. The application for the 630 Patent was filed on August 1, 1997, and a priority claim was made based on a US application filed in 1996 [59]. However, s 28.4(4) provides that where there are two or more previous applications on which priority could be claimed, the earliest must be used. The 1996 US priority application itself claimed priority from another US application which was filed in 1992. Hospira argued that the priority claim to the 1996 application was therefore invalid (with the result that the claim date would be the Canadian filing date, making additional prior art relevant) [60].

Per s 28.1, priority cannot be claimed from the 1996 application unless it discloses the same subject-matter as the 630 patent; and the effect of 28.4(4) is that priority must be claimed from the 1992 application if the 1992 application discloses the same subject-matter as the 630 patent. The question for both was therefore whether they disclosed the same subject matter as the 630 patent. Neither priority application was in evidence. Thus the argument, and Locke JA’s holding, turned on the burden of proof.

Hospira argued that the patentee had the burden to establish the priority claim, and it failed to meet that burden because it did not put the 1996 application into evidence. Kennedy Trust, on the other hand, argued that the burden of proof was instead on Hospira in light of the presumption of validity per s 43(2) of the Act.

Locke JA rejected both these positions [63]. He held that that Hospira’s reliance on the 1992 priority “is remote enough from the issue of the priority claim on the 630 Patent” that Hospira had the burden to prove the contents of the 1992 priority” [64]. It seems reasonable to me that the party asserting a particular priority date should have the obligation to prove it. Given that burden, there is a separate question of how to actually prove the contents of the earlier priority application. At trial Hospira seemed to have relied on the fact that Kennedy Trust had actually pursued an appeal to the USPTO to establish that the 1996 application was entitled to claim priority to the 1992 priority, essentially on the basis that it disclosed the same subject-matter [FC 157]. Locke JA did not specifically discuss why this was not sufficient to carry the burden (and it's not clear that issue was even raised on appeal). Given that the 1996 application was not in evidence, evidence that the 1992 priority disclosed the same subject matter as the 1996 application may not be sufficient proof that either disclosed the same subject matter as the 630 patent.

Turning to Kennedy Trust’s argument, Locke JA held that the presumption of validity does not extend to the priority claim because the claim date only affects the prior art, and does not go directly to validity [63]. That seems right to me on the text of s 43(2). But if the presumption of validity does not apply and the 1996 application itself was not introduced into evidence, what is the basis for holding that the 1996 priority claim was valid? Locke JA held that “With no dispute that the 1996 priority supports the subject matter of the claims in issue” and in the absence of evidence of the contents of the 1992 priority, he saw no error in recognizing the 1996 claim date [65]. I must say that this looks to me like the application of some kind of presumption of validity, given that there was no evidence at all about the contents of the 1996 application. (Hospira’s position at trial was that both the 1992 and the 1996 disclosed the same subject matter, but that doesn’t necessarily imply that either discloses the same subject matter as the 630 patent.) Would the result have been different if Hospira had asserted, without any evidence, that the 1996 application did not disclose the same subject matter as the 630 patent? Would that have been enough of a dispute to require the patentee to introduce the 1996 application? If not, it would seem that some kind of presumption is at work. But, as noted, Locke JA expressly held that the presumption of validity does not extend to a priority claim.

In any event, in either case it does seem that the best way of establishing the content of the priority application is directly, by introducing it into evidence.