Therasense, Inc. v. Becton-Dickinson, Inc.
United States Court of Appeals for the Federal Circuit
649 F.3d 1276 (Fed. Cir. 2011)
Abbott Laboratories, Therasense's (defendant) predecessor, told the U.S. Patent and Trademark Office that a protective membrane was a required, non-optional feature of its glucose test strip invention, while its European patent counsel had told the European Patent Office the opposite -- that the membrane was merely preferred, not required -- without disclosing that contrary statement to the PTO. Becton-Dickinson, Inc. (plaintiff) sued for a declaratory judgment that Abbott's patents were invalid; the district court found the patents unenforceable for inequitable conduct, a Federal Circuit panel affirmed, and the full court granted rehearing en banc.
Whether but-for materiality -- that the patent office would not have granted the patent had it known the omitted information -- is required to establish the materiality element of inequitable conduct.