In Nature Simulation Systems Inc. v. Autodesk, Inc., No. 2020-2257 (Fed. Cir. Jan. 27, 2022), the Federal Circuit reversed the ND Cal’s determination of indefiniteness, holding “that the district court erred on the legal standard for claim indefiniteness, and that on the correct standard the claims are not indefinite.” Reference was made to the Supreme Court’s Nautilus decision, holding that the claims “must provide reasonable certainty in defining what is patented” when “viewed and understood in the context of the specification and the prosecution history.” The Federal Circuit concluded that the district court erred in applying an “unanswered questions” test for indefiniteness. The district court “declined to consider information in the specification that was not included in the claims” and gave “no weight to the prosecution history showing the resolution of indefiniteness by [the Examiner] adding … designated technologic limitations to the claims.” We’ve known since Phillips v. AWH Corp., 415 F.3D 1303 (2005) (EN BANC) that in claim construction priority is placed on the intrinsic record.