The Doctrine of Equivalents May Apply Despite Restriction Requirements and Narrow Claiming

| Karen Cassidy Selvaggio


Before Taranto, Schall, and Chen. Appeal from the United States District Court for the District of Delaware.

Summary: Application of the doctrine of equivalents may not be barred by: (1) prosecution history estoppel where an election in response to a restriction requirement does not constitute a surrender of an asserted equivalent or (2) intentional narrow claiming where there is insufficient evidence that the asserted equivalent was foreseeable.

UCB filed suit against Defendants Watson and Actavis asserting a patent relating to a transdermal form of a drug for treating Parkinson’s disease. The district court found that Defendants infringed all of the asserted claims of the patent under the doctrine of equivalents. While Defendants’ products used a different adhesive than the claimed adhesives, the district court determined that, under the doctrine of equivalents, the differences between Defendants’ adhesives and the claimed adhesives were insubstantial. The district court also rejected Defendants’ arguments that UCB was barred from asserting the doctrine of equivalents. Defendants appealed.

On appeal, the Federal Circuit first agreed with the district court that UCB was not barred from asserting the doctrine equivalents. Regarding prosecution history estoppel, the Federal Circuit disagreed with Defendants’ reading of the prosecution history, noting that the restriction requirement did not relate to Defendants’ adhesive and that UCB never added a limitation excluding Defendants’ adhesive by amendment. Accordingly, the Federal Circuit concluded that UCB’s election in response to the Examiner’s restriction was not a narrowing amendment, and did not indicate a surrender of Defendants’ adhesive as an equivalent. Next, the Federal Circuit rejected Defendants’ argument that UCB chose to draft narrow claims and therefore should not be permitted to expand the scope of those claims through the doctrine of equivalents. While recognizing that foreseeability of an asserted equivalent at the time of claim drafting is a factor to consider in determining whether the doctrine of equivalents should apply, the Federal Circuit determined that there was not enough indication from the patent specification, claims, or the record evidence of the inventor’s knowledge to conclude that UCB surrendered Defendants’ adhesive as an equivalent for infringement purposes. The Federal Circuit also rejected Defendants’ claim vitiation and ensnarement arguments. Finding no clear error in the district court’s application of the doctrine of equivalents, the Federal Circuit affirmed.

Editor: Paul Stewart