Two weeks ago the Supreme Court consented to the filing of amicus briefs in the Teva v. Sandoz case. This case will resolve the split in the Federal Circuit over the standard of review for patent claim construction. This is a good time to review the prior case law and the existing standard of review.

The Federal Circuit established the current standard of review for claim construction in Cybor Corp. v. FAS Technologies., 138 F.3d 1448 (Fed. Cir. 1998).  Prior to that decision, the standard of review had been inconsistent; sometimes claim construction was considered a factual inquiry, while others it was treated as a pure question of law.   However, in Cybor the Federal Circuit en banc definitively held that claim construction, including “any allegedly fact-based questions relating to claim construction,” was a purely legal question and was reviewed de novo on appeal.    This represented an extension of the Supreme Court’s holding in Markman II that claim construction is a question for the court.    The Cybor court reasoned that claim construction should be classified a pure legal question, rather than a mixed question of fact and law, because one judicial actor–the judge–is better positioned to decide the issue in question.   Further, the court reasoned that even if the claim construction is “enlightened by extrinsic evidence,” it is not based on factual evidentiary findings.  Id. Rather, claim construction is a process of interpreting legal texts¾patent documents and prosecution history¾and is therefore a matter of law.  Id.

The proper standard of review of patent claim construction has been contested since the Cybor decision. Chief Judge Mayer, Judge Newman and Judge Rader disagreed with the Cybor majority’s conclusion that the Supreme Court considered claim construction a purely legal question reviewed de novo.  They disagreed with the majority’s interpretation of Markham II; instead they felt that the Supreme Court had intimated that claim construction was not a purely legal matter.    Further, they predicted that de novo review would undermine the values of certainty and predictability sought in Markman.   The internal debate over the Cybor standard has persisted over time.  Although the Federal Circuit has revisited the issue of the proper standard of review for claim construction, it had not rendered a decision en banc until Lighting Ballast.

The dispute in Lighting Ballast concerns patented technology for the control and protection circuits for electronic lighting ballasts commonly used in fluorescent lighting.  The patent at issue claims “a device comprising: voltage source means providing a constant or variable magnitude DC voltage. . . .” U.S. Patent. No. 5,436,529 (filed Apr. 22, 1993).  Based on expert testimony, the district court construed the term “voltage source means” to correspond to a structure capable of supplying useable voltage to the device.    On appeal, the Federal Circuit panel reviewed the district court’s claim construction de novo and found that the term was instead a means–plus-function limitation under 35 U.S.C. § 112.  Id.  Lighting Ballast petitioned the court for rehearing en banc, arguing that Cybor should be overruled because claim construction is not purely a question of law.

The Federal Circuit granted the petition for rehearing en banc, and in a 6-4 decision, confirmed the standard of de novo review established in Cybor.  The majority decision filed by Judge Newman and joined by five other judges (Judges Lourie, Dyk, Prost, Moore, and Taranto), rested heavily on the values of stare decisis.  See id. at 1281.  It emphasized the importance of stability and consistency in patent law, repeating the Supreme Court’s advice that “courts should be ‘cautious before adopting changes that disrupt the settled expectations of the inventing community.’”   The majority concluded that the petitioner had failed to demonstrate a clear benefit or advantage conferred by overturning Cybor; Lighting Ballast had not offered “argument of public policy, or changed circumstances, or unworkability or intolerability, or any other justification.”  Id. at 1286.  In the dissent, Chief Judge Rader and Judges O’Malley, Reyna, and Wallach argued that stare decisis did not justify adherence to the Cybor standard because it “misapprehends the Supreme Court’s guidance, contravenes the Federal Rules of Civil Procedure, and adds considerable uncertainty and expense to patent litigation.”

One month after the Federal Circuit’s en banc decision in Lighting Ballast, the Supreme Court granted certiorari on the question of the proper standard of review for patent claim construction.  Teva turns on the interpretation of the term “molecular weight” in claims for a drug used to treat multiple sclerosis.  In July 2013, the Federal Circuit panel decision overturned the district court’s interpretation of the term “molecular weight” as being indefinite; as a result, the panel found the patents valid and infringed by Teva and other competitors’ proposed generic versions of the drug.  After its petition for rehearing was denied, and while the question was pending before the en banc Federal Circuit in Lighting Ballast, Teva petitioned the Supreme Court for certiorari.  Id. at 2-4.  The Supreme Court granted certiorari, but the case has not yet been set for argument.

–Emily Gabranski

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