Reasonable Certainty In Patent Claim Terminology Post-Nautilus

(April 26, 2024) - Venable attorney Donald H. Heckenberg Jr. explains how the standard for determining whether a patent is invalid as indefinite has been applied in varied contexts.

Ten years have passed since the Supreme Court's decision in Nautilus, Inc. v. Biosig Instruments, Inc. establishing the reasonable certainty test for determining whether patent claims are indefinite under 35 U.S.C.A. § 112.¹

Many thought immediately following the Nautilus decision that the reasonable certainty test would result in patent claims being found invalid more often than under the previous test for indefiniteness. But cases from the U.S. Court of Appeals for the Federal Circuit show that reasonable certainty is not as high of a bar as may have been thought; exacting precision in claim terminology is not required under the Nautilus test.