In Lighting Ballast Control LLC, v. Philips Electronics North America Corporation, [2012-1014] (February 21, 2014), the Federal Circuit en banc held that claim construction is a matter of law that is subject to de novo review on appeal, confirming the continued validity of its en banc decision in Cybor Corp. v. FAS Technologies, Inc., 138 F.3d 1448 (Fed. Cir. 1998).

In an opinion by Judge Newman, the Court relied upon principles of stare decisis, finding that “[a]fter fifteen years of experience with Cybor, we conclude that the court should retain plenary review of claim construction, thereby providing national uniformity, consistency, and finality to the meaning and scope of patent claims.”  The Court said that experience has confirmed that Cybor is an effective implementation of Markman II, and that the criteria for departure from stare decisis are not met.