Determining what the claims of a patent mean, i.e., claim construction, is largely considered the single most important issue in any patent case. It impacts virtually every claim or defense in a patent infringement lawsuit and in many instances drives disposition of a case. On Sept. 13, 2013, the Court of Appeals for the Federal Circuit sat en banc in Lighting Ballast Control LLC v. Philips Electronics North America Corporation and Universal Lighting Technologies, Inc. to address the standard of review to be applied to a district court’s claim construction ruling. This was only the fourth time in 20 years that the Federal Circuit had sat en banc to address the contours of the claim construction process. In particular, in Lighting Ballast, the Federal Circuit asked the parties to address the following questions:
- Should the Federal Circuit overrule Cybor Corp. v. FAS Techs., Inc. (in which the Federal Circuit held that “as a purely legal question, we review claim construction de novo on appeal including any alleged fact-based questions relating to claim construction”)?
- Should the Federal Circuit afford deference to any aspect of a district court’s claim construction?
- If so, which aspects should be afforded deference?
While both parties of the Lighting Ballast case agree that Cybor’s de novo standard of review should not be applied to all aspects of a district court’s claim construction ruling and thus should be modified in some way, they agree on little else. Lighting Ballast seeks complete abandonment of the de novo standard of review and argues that an appellate court should afford deference to all aspects of a district court’s claim construction ruling. Under this standard, a district court’s claim construction ruling could only be reversed if the appellate court determined the ruling was clearly erroneous.