Relying in part on evidence that a district court’s claim construction excluded a preferred embodiment, which was the subject of a dependent claim, the U.S. Court of Appeals for the Federal Circuit explained that the “explicit definition” of a claim term provided in the patents did not limit the term’s meaning. On that basis, the Federal Circuit vacated the claim construction and subsequent summary judgment of infringement. The Court also overturned summary judgments of invalidity for lack of written description and lack of enablement. ButamaxTM Advanced Biofuels, LLC v. Gevo, Inc., Case No. 13-1342 (Fed. Cir., Feb. 18, 2014) (Linn, J.).
Butamax owns patents covering recombinant microbes that use a particular biosynthetic pathway to produce isobutanol, a fuel additive. The parties’ dispute concerned the meaning of the claim term keto-acid reductoisomerase (KARI), an enzyme used in that pathway. Butamax argued for the plain meaning, which both parties agreed to be an enzyme that uses either nicotinamide adenine dinucleotide + hydrogen (NADH) or nicotinamide adenine dinucleotide phosphate + hydrogen (NADPH) as cofactors. Gevo, meanwhile, argued that the patentees expressly limited this term by defining the enzyme as “using” NADPH and by describing it by reference to a particular enzyme classification (EC) number in the term’s definition and in an asserted claim. Evidence showed that enzymes bearing that EC number were known to use NADPH as a cofactor. The district court agreed with Gevo and adopted the narrower construction. Butamax appealed.
Relying on several sources of intrinsic evidence that conflicted with this construction, the Federal Circuit overturned the disputed claim construction. The Court found that the district court’s construction excluded a preferred embodiment, which was also the subject of a dependent claim. The EC number provided in the definition and the claims referenced a mutant KARI known to use NADH as a cofactor. The prosecution history also provided an example of a KARI used in the claimed invention that has NADH as a cofactor. The Court relied on the principle that claims are not normally construed to exclude embodiments disclosed in the specification, concluding that the patentee did not evidence a clear intent to redefine KARI and that the disputed term retained its plain and ordinary meaning.
In light of the proper claim construction, the Federal Circuit determined held that a genuine issue of material fact on infringement may exist and remanded that question to the district court.
Regarding written description, the Federal Circuit explained that an affidavit and supporting references offered by Gevo that were not addressed by the district court raised a genuine dispute of material fact that precluded summary judgment in favor of Butamax on this issue. The Court thus overturned the district court’s ruling and vacated the order stating that two claims lacked enablement (which it concluded was a scrivener’s error because Gevo did not challenge the asserted claims on that basis).