A split en banc Federal Circuit Court of Appeals has declined an invitation to overturn 15-year-old precedent and determined that “appellate review of district court decisions concerning the meaning and scope of patent claims—called ‘claim construction’”—will remain de novo, thus requiring no deference on appeal to the district court’s interpretation of patent claims. Lighting Ballast Control LLC v. Philips Elec. N. Am. Corp., No. 2012- 1014 (Fed. Cir., decided February 21, 2014). so ruling, the court reinstated a panel ruling that applied the correct appellate standard.

The issue generated 21 amicus curiae briefs on behalf of 38 entities presenting three general views, which the majority summarized in defending its position 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 totality of experience has confirmed that Cybor [Corp. v. FAS Technologies, Inc., 138 F.3d 1448 (Fed. Cir. 1998),] is an effective implementation of Markman II [Markman v. Westview Instruments, Inc., 517 u.s. 370 (1996), (Markman II), aff’g, Markman v. Westview Instruments, Inc., 52 F.3d 967 (Fed. Cir. 1995) (en banc) (Markman I)], and that the criteria for departure from stare decisis are not met.”

The four dissenting judges called the majority opinion “surprising” and noted, “[c]riticism of and debate over Cybor have been widespread since it issued—not only among legal scholars and patent practitioners, but also among members of this court.” Focusing on the U.S. Supreme Court’s Markman II ruling, the dissent states, “construing the claims of a patent at times requires district courts to resolve questions of fact. And, [the majority] puts itself at odds with binding congressional and supreme Court authority when it refuses to abide by the requirements of Rule 52(a) (6) of the Federal Rules of Civil Procedure, which expressly instructs that, on appeal, all “findings of fact . . . must not be set aside unless clearly erroneous.”