The chief judge of the U.S. Court of Appeals for the Federal Circuit has gone to war with two of her colleagues over pharmaceutical patents and high drug prices.

Chief Judge Sharon Prost issued a dissenting opinion Friday in GlaxoSmithKline v. Teva that accused the majority of "nullifying" federal law that permits the marketing of generic drugs for non-patented uses. Prost said the decision was particularly unfortunate because GlaxoSmithKline had earned $7.1 billion from a decade-long "monopoly" on an anti-hypertension medication before obtaining a new use patent for congestive heart failure.