On January 20, 2015, the Supreme Court issued its decision in
Teva Pharm. USA, Inc. v. Sandoz, Inc.,135 S. Ct. 831
(2015) and changed the standard of deference for claim
construction. Previously, all claim construction decisions were
reviewed de novo by the Federal Circuit, whether or not
the decision involved any evidentiary underpinnings, such as
extrinsic evidence or expert testimony. In Teva, the Court
held that subsidiary factual findings about extrinsic evidence
should be reviewed for clear error on appeal.
The patent in Teva covers a multiple sclerosis drug,
Copaxone. After Sandoz tried to market a generic version of the
drug, Teva sued for patent infringement. Sandoz argued that the
patent was invalid because a claim term was indefinite. The claim
required the active compound to have "a molecular weight of 5
to 9 kilodaltons." Sandoz argued that the claim did not meet
the definiteness requirement under 35 U.S.C. § 112
because it did not state which of three
