In Teva Pharm. USA, Inc. v. Sandoz, Inc., No. 2012-1567 (Fed. Cir. June 18, 2015), the Federal Circuit, on remand from the Supreme Court, held that certain of Teva’s patent claims covering its multiple sclerosis drug, Copaxone®, were invalid for indefiniteness under the “reasonable certainty” standard recently established in Nautilus, Inc. v. Biosig Instruments, Inc., 134 S. Ct. 2120 (2014).

The asserted claims of Teva’s U.S. Patent No. 5,800,008 (“Teva’s ’008 patent”) recited a “copolymer-1 having a molecular weight of about 5 to 9 kilodaltons.” The district court found that the “molecular weight” element could be calculated by any of three different measures—Mp (peak), Mn (number), and Mw (weight) average molecular weight. Relying principally on Teva’s expert testimony, the district court construed it as Mp (peak) and found the corresponding claims sufficiently definite.

The Federal Circuit initially applied a de novo review standard and reversed the district court, finding the claim term indefinite, but the Supreme Court granted certiorari and reversed the Federal Circuit, holding that the Federal Circuit must review underlying factual findings concerning claim construction for clear error. While the appeal was pending, the Supreme Court also issued its decision in Nautilus, replacing the “insolubly ambiguous” test for indefiniteness with a “reasonable certainty” standard.

On remand, the Federal Circuit reviewed for clear error several factual findings of the district court relating to the meaning of “molecular weight” as used in Teva’s ’008 patent claims and concluded that they were not clearly erroneous. The Federal Circuit stated, however, that accepting those fact findings did not, as Teva suggested, mean there existed a presumption as to the meaning of this particular language in Teva’s ’008 patent claims. Instead, looking to the claim language, specification, and prosecution history of Teva’s ’008 patent, the Federal Circuit found that a skilled artisan “would still not be reasonably certain in light of the entire record as to which type of average [weight] was intended” in Teva’s ’008 patent claims.

Judge Mayer dissented, stating that the majority was “once again led astray by its failure to afford sufficient deference to the trial court’s findings of fact.” Judge Mayer stated that the majority “takes the opposite tack, first embarking on an independent review of the record and then considering, as an afterthought, the important and carefully considered factual findings made by the trial court.”