In Nalpropion Pharmaceuticals v. Actavis Laboratories FL, Inc., No. 2018-1221 (Fed. Cir. Aug. 15, 2019), the Federal Circuit reviewed whether a claim reciting a specific dissolution profile collected using the USP Apparatus 2 Paddle Method had written description support when the specification disclosed several tables of dissolution profile data collected using the USP Apparatus 1 Basket Method. The district court below found written description support based on the plaintiff’s expert’s statement that the claimed dissolution profile and the dissolution profile data in the specification in this particular case were “substantially equivalent.” In finding no error to overturn the district court, the Federal Circuit noted that because the written description question in this particular case related to resultant dissolution parameters rather than an operative claim step, using substantial equivalence to show possession was acceptable. Further discussion of the decision can be found on Finnegan’s Federal Circuit IP Blog.