In our January Newsletter (here) we reported on the non-precedential Federal Circuit decision in Daiichi Sankyo Co. v. Seagen Inc., Fed. Cir. Dec 02, 2025, appeal 2023-2424, holding that Seagen’s U.S. Patent 10,808,039 (‘039) was invalid for lack of written description and enablement, over turning a jury verdict and JMOL to the contrary. This was the second time in a two-week period that the Court had overturned jury verdicts in favor of the patentee on written description. As the Court recognized in the earlier decision Duke Univ. et al. v Sandoz, Inc., 160 F.4th 1305 (2025) “a district court’s refusal to grant judgment as a matter of law may be reversed only if the evidence is such that without weighing the credibility of the witnesses the only reasonable conclusion is in the moving party’s favor.” This is a high burden to meet.
