Functional limitations and Senju Pharm. v. Lupin Pharm.
Last year in Senju Pharma. v. Apotex Inc., 746 F.3d 1344 (Fed. Cir. 2014), Senju and Allergan were blocked from suing Apotex on a re-examined set of claims under the doctrine of claim preclusion. However, while claim preclusion stops Senju and Allergan from suing Apotex, claim preclusion is no barrier to an infringement suit against any other manufacturer wishing to sell a generic version of Allergan’s Zymar® ophthalmic drops.
When Lupin Pharmaceuticals and Hi-Tech Pharmacal filed ANDAs seeking to market generic versions of Zymar®, Senju and Allergan sued for infringement. The U.S. District Court for the District of Delaware—in fact, the same judge who had presided over the original suit against Apotex—ruled that the re-examined claims were all invalid for obviousness over exactly the same art combinations over which the earlier claims were held obvious. On appeal the Federal Circuit affirmed.
The obviousness analysis here largely followed the shape of the analysis that the Federal Circuit had earlier affirmed. Senju Pharma. v. Apotex Inc., 836 F. Supp.2d 196 (D. Del. 2011), aff’d. at 485 Fed. Appx. 433 (Fed. Cir. 2012). Senju and Apotex waged a battle of experts, and the district court found Apotex’s expert more credible. Perhaps the most interesting aspect of the parties’ argument about obviousness is that the patentee had argued that the effects of their claimed composition on corneal permeability should be taken into account in assessing the obviousness of the claims as a whole. Although this might have seemed a rather ordinary way to assess the obviousness of a chemical composition (In re Papesch, 315 F.2d 381, 391 (C.C.P.A. 1963)), the Federal Circuit held that the district court properly excluded such considerations because the relevant corneal permeability limitations are not recited in the composition claims. Senju v. Apotex, slip op. at 18.
This is just the most recent sign post along a road that the Federal Circuit has been walking for a few years now, going back at least to Allergan v. Sandoz, 726 F.3d 1286 (Fed. Cir. 2013). The good news for patentees is that the Federal Circuit is increasingly willing to consider functional claim limitations as imparting patentability, almost regardless of the recitation of structural features that give rise to the functional advantages. Ferring BV v. Watson Labs, 764 F.3d 1401, 1408 (Fed. Cir. 2014). The bad news, however, is that the court is increasingly unwilling to consider unexpected results arguments unless the results are speciﬁed in the claims—dismissing the assertion of a result not mentioned in the claims as a case of reading limitations from the speciﬁcation into the claims. Senju v. Apotex, slip op. at 18.
Practice tip: Go “all in” when it comes to functional limitations and unexpected results. If there are particularly advantageous results known to the applicant during prosecution, be sure to include them in at least a dependent claim.