On May 4, 2026, the United States Court of Appeals for the Federal Circuit (Judges Lourie, Prost, and District Judge Burroughs) affirmed a decision of the United States District Court for the Eastern District of Arkansas holding that asserted claims of U.S. Patent No. 10,912,321 (“the ‘321 patent”) were invalid as indefinite under 35 U.S.C. § 112(b).  Enviro Tech Chem. Servs., Inc. v. Safe Foods Corp., No. 2024-2160 (Fed. Cir. May 4, 2026).  The decision addresses the circumstances under which a term of approximation renders a patent claim indefinite, particularly when the specification provides conflicting guidance and the prosecution history reflects inconsistent treatment of the term.