In a long-awaited decision, the Federal Circuit ruled en banc to uphold the the de novo standard for appellate review of claim construction issues, which was previously established in another en banc decision, Cybor Corp. v. FAS Technologies, Inc. 138 F.3d 1448 (Fed. Cir. 1998).
The facts and procedural background of the case presented a prime opportunity for the Federal Circuit to revisit the question of what deference, if any, it should give to a district court’s claim constructions. During the district court proceedings, the parties disputed the meaning of “voltage means.” As per usual, the district court analyzed the patent’s intrinsic evidence relating to the claim term. However, the district court also accepted testimony from expert witnesses and the inventor. After analyzing the different types of evidence, the district court sided with the patentee and ruled that the term should be given its plain meaning, as opposed to a more specific meaning as a means-plus-function term.
Applying the non-deferential Cybor standard of review, a panel from the Federal Circuit reversed the district court’s claim construction. The panel held that the term is a means-plus-function term and required disclosure of sufficient corresponding structure in the patent specification. Based on that conclusion, the panel invalidated the claims for indefiniteness. The patentee requested rehearing, arguing that the interpretation of documents is a fundamentally factual exercise and, therefore, a district court’s interpretation of patent claims requires some deference on appeal. In this case, the patentee argued that, on a deferential review, the district court would not, or should not, have been reversed. The Federal Circuit undertook rehearing en banc for the purpose of reconsidering the standard of appellate review of claim construction.