2,298,059 / tenofovir (PMPA) / TRUVADA
In Gilead v Teva / tenofovir (NOC) 2013 FC 1272, the companion case to 2013 FC 1270 (blogged here), Barnes J refused to grant an order of prohibition to Gilead on the basis that the 059 patent was obvious. Teva had put in issue the validity of Claims 1 through 7, but Gilead had relied on on Claims 3 and 4 -. Apotex then served an NOA on Gilead alleging obviousness  and also alleging an abuse of process. Gilead responded by saying it intended to fill in an evidentiary gap from the earlier proceeding  and that it relied on all the Claims, not just 3 and 4 . Barnes J held that Gilead’s response was indeed an abuse of process:
 It seems to me that an abuse of process finding in the NOC context is not dependant on the evidence to be called but, rather, on the issues presented to the Court for determination. Once the second person puts a validity issue into play, the patentee proceeds at its subsequent peril by not fully responding. In other words, it must live with the consequences of not fully joining issue in the first proceeding.
 A patentee cannot avoid an abuse of process finding by asserting the validity of only a select number of claims in an initial NOC proceeding, only to assert the validity of different claims in a subsequent NOC proceeding involving a different generic challenger. Where the initial NOA puts in issue the validity of certain patent claims, it is not open to the patentee to concede some of the claims but later resile from that position. If it were otherwise, the patentee could effectively split its case and unilaterally compel subsequent generic challengers to litigate claims, the invalidity of which the patentee had effectively conceded. This would amount to a manipulation of the system and it would violate the principle that the patentee is required to put its strongest case forward in the first instance.
 The situation may well be different where the initial generic challenger declines to put the validity of certain claims in issue in its NOA, perhaps relying solely on an allegation of non-infringement. There the patentee could presumably rely on the presumption of validity in the first instance without compromising its right to assert validity in the face of a subsequent challenge.