The Federal Circuit held that a lack of approximation language in a claimed range is not dispositive and may leave room for ambiguity which can require consideration of extrinsic evidence to determine the bounds of the claim.
The Federal Circuit, in Actelion Pharmaceuticals Ltd. v. Mylan Pharmaceuticals Inc., No. 2022-1889 (Fed. Cir. Nov. 6, 2023), held that a lack of approximation language in the claimed range of “a pH of 13 or higher” was not dispositive as to whether the claim could encompass pH values below 13, which would round to 13 (e.g., 12.5). As the Federal Circuit found ambiguity on this issue in the intrinsic evidence, the Court held that the district court committed error by failing to address the submitted extrinsic evidence and remanded to require such consideration.