On February 21, 2014, a divided Federal Circuit decided in Lighting Ballast v. Philips Electronics to follow its 1998 decision in Cybor v. FAS Technologies regarding the degree of deference—or standard of review—to apply when evaluating claim constructions by district courts.

Six of the ten judges who heard arguments in the Lighting Ballast case decided that the court will continue to review claim constructions de novo, that is, for correctness as a matter of law. The six-judge majority confirmed the Cybor ruling that the de novo standard applies to all aspects of claim construction, including any allegedly fact-based questions. The majority relied on the doctrine of stare decisis, under which courts adhere to earlier decisions on questions of law to ensure certainty, consistency, and stability in the administration of justice unless sound reasons warrant change. 

The Cybor ruling has sparked much criticism and debate. For instance, the ABA in 2004 adopted the resolution that “an appellate court should review only by the clearly erroneous standard any underlying findings of fact made by a trial court in connection with construing a claim term.” 

Recognizing the controversy concerning the Cybor ruling, the Federal Circuit decided to revisit it in a case brought by patentee Lighting Ballast against Universal Lighting, where the litigants disputed the meaning of the claim language “voltage source means.” The district court initially construed that phrase as a means-plus-function element, thus covering “the corresponding . . . structure described in the specification and equivalents thereof” according to 35 U.S.C. § 112(f). Because the specification contained no corresponding structure for the claimed “voltage source means,” the district court held the claims invalid as indefinite. 

Lighting Ballast requested reconsideration, and the district court reversed its indefiniteness decision. Citing evidence from a Lighting Ballast expert and an inventor, the court ruled that means-plus-function claiming under § 112(f) did not apply and that a skilled artisan would understand “voltage source means” according to its ordinary meaning in the art. After a jury trial, the district court entered judgment in Lighting Ballast’s favor.

Universal Lighting appealed to the Federal Circuit. In January 2013, a three-judge panel agreed with the district court’s initial claim construction and held the claims invalid as indefinite. But in March 2013, the Federal Circuit granted Lighting Ballast’s petition for rehearing en banc and vacated the panel decision. In doing so, the court directed the parties to brief the following issues: (1) should the court overrule Cybor; (2) should the court afford deference to any aspect of a district court’s claim construction; and (3) if so, which aspects should be afforded deference.

The six-judge majority decided not to overrule Cybor because no sound reasons warranted a departure from that fifteen-year-old precedent. The majority started by observing that the doctrine of stare decisis provides stability in the law and “enhances predictability and efficiency in dispute resolution and legal proceedings.” It then quoted the Supreme Court’s statement that courts should be “cautious before adopting changes that disrupt the settled expectations of the inventing community.” 

The majority then considered whether post-Cybor developments have undermined its reasoning. It discussed extensive patent-related legislative activity in recent years and viewed Congressional inaction on claim-construction procedure as favoring the application of stare decisis.

The majority next considered whether Cybor has proved unworkable. It determined that overruling or modifying Cybor to introduce a fact/law distinction would have “a high potential to diminish workability and increase burdens.” Regarding workability, the majority reasoned that no one has proposed a workable replacement standard delineating what constitutes fact and what constitutes law. As for burden, the majority believed that an “amorphous” or “undefined” replacement standard would increase the burden for courts and litigants by engendering threshold litigation regarding what constitutes fact and what constitutes law. Thus, the majority concluded that stare decisis counseled against “overturning precedent when there is no evidence of unworkability and no clearly better resolution.”

In addition, the majority believed that maintaining de novo review for all aspects of claim construction will promote uniformity and consistency in the treatment of patents, which are often asserted against different defendants in different district courts. 

The majority did not address the meaning of “voltage source means” but simply reinstated the panel’s decision holding the claims invalid as indefinite. 

According to the four judges who dissented, Supreme Court statements indicate that claim construction can present questions of fact. Because Rule 52(a) of the Federal Rules of Civil Procedure provides that “findings of fact . . . must not be set aside unless clearly erroneous,” the four-judge minority maintained that the “clearly erroneous” standard should apply to any questions of fact relating to claim construction. 

Due to the issue’s importance, Lighting Ballast will likely seek Supreme Court review, which the Court may allow in view of the fractured Federal Circuit. When different federal appellate circuit courts adopt different rules or legal interpretations, a circuit split results. Many of the cases that the Supreme Court reviews involve circuit splits. Since only the Federal Circuit has jurisdiction to consider patent cases, the six-four decision in Lighting Ballast approximates a circuit split. Along similar lines, the Supreme Court in January 2014 chose to review a six-five Federal Circuit decision inAkamai Technologies v. Limelight Networks regarding divided infringement of method claims. The Court has scheduled oral argument inAkamai for April 30, 2014.