On May 13, 2026, the U.S. Court of Appeals for the Federal Circuit (Judges Reyna, Taranto, and Stoll) affirmed a decision of the U.S. District Court for the Northern District of West Virginia finding that defendant does not infringe U.S. Patent Nos. 8,318,802 and 8,598,227 (collectively, the “’802” and “’227” patents), either literally or under the doctrine of equivalents.  Actelion Pharmaceuticals Ltd v. Mylan Pharmaceuticals Inc., No. 2024-1641 (Fed. Cir. May 13, 2026).  The decision addresses how pH measurements recited in pharmaceutical patent claims should be interpreted, and the application of prosecution history estoppel and the disclosure-dedication rule to bar equivalents-based infringement theories. 

On January 28, 2021, the U.S. District Court for the Northern District of California (NDCA) issued an order granting summary judgment of noninfringement under the doctrine of equivalents.  Fluidigm Corp. v. IONpath, Inc., Case No. 3:19-cv-05639-WHA, Dkt. No. 210 (N.D. Cal. Jan. 28, 2021).  The NDCA found that the patentee “abdicated” its burden under the doctrine of equivalents by refusing to engage in the hypothetical claim analysis required under defendant’s ensnarement defense.