Before Moore, Mayer, and Stoll. Appeal from the United States District Court for the District of New Jersey.

Summary: Plain claim language will not be narrowed based on a patent’s specification unless the patentee clearly and explicitly disclaims claim scope.

Defendants filed ANDAs to obtain approval to market generic versions of the schizophrenia and bipolar drug LATUDA, the active ingredient for which is lurasidone. Plaintiffs thereafter sued Defendants for allegedly infringing a patent covering the lurasidone compound. While lurasidone can exist in two distinct three-dimensional structures that are mirror images of one another (“enantiomers”), only the (-) enantiomer was depicted in the claim at issue. Defendants argued for a construction that limited the claimed compound to a “racemic” (50/50) mixture of the two enantiomers based on similarities between the claimed compound and one disclosed in the specification and based on citations to chemistry textbooks suggesting the claimed structure is a shorthand representation for a racemic mixture. The district court disagreed and held that the claimed compound’s resemblance to a mixture disclosed in the specification did not justify importing limitations from the specification into the claim. The district court agreed with Plaintiffs’ proposal to interpret the claim to cover both enantiomers and mixtures thereof. Defendants conceded infringement under this construction but filed an appeal.

The Federal Circuit affirmed the district court’s construction to the extent that the disputed claim at least covered the (-) enantiomer, which was enough to resolve the parties’ dispute. The Federal Circuit held that the plain language of the claim negated a limiting interpretation because the claim explicitly showed the (-) enantiomer and failed to include any language limiting claim scope to a racemic mixture. Thus, the Defendants’ proposed construction would exclude what was expressly shown in the claim. The Federal Circuit also found no evidence in the specification that the claim was intentionally linked or described as coextensive with a racemic mixture, or that the specification included a clear disclaimer of claim scope. Although acknowledging Defendants’ arguments based on extrinsic evidence, the Federal Circuit found no clear error in the district court’s rejection of the chemistry textbooks as irrelevant or contradictory.