The evolving standard for patent claim definiteness

The recent opinion in BASF Corp. v. Johnson Matthey Inc., 875 F.3d 1360 (Fed. Cir. 2017), clarified the "reasonable certainty" standard for patent claim definiteness established by the U.S. Supreme Court in Nautilus, Inc. v. Biosig Instruments, Inc., 134 S. Ct. 2120 (2014). In BASF Corp., the U.S. Court of Appeals for the Federal Circuit stated that the context in which a skilled artisan would understand the claims (as described by intrinsic evidence) is important to determine whether the claims are indeed definite.

Patent Claim Definiteness

Patent claims spell out the metes and bounds of an invention and put the world on notice of what is and what is not infringement. The doctrine of claim definiteness requires that patent claims "particularly point out and distinctly claim" the invention. 35 U.S.C. Section 112(b). The purposes of claim definiteness are to ensure that claim scope is clear so that the public is informed of what constitutes infringement of the patent and to provide a clear measure of the invention, so that it can be determined whether the claimed invention meets the criteria for patentability.

The Supreme Court established the most recent standard for claim definiteness in Nautilus, holding that the claims, when read in light of the specification, must inform a skilled artisan about the scope of the invention "with reasonable certainty." The Patent Office uses a different (and stricter) standard for claim definiteness, instructing that once claims are given their "broadest reasonable interpretation" consistent with the specification, the claims should set out and circumscribe the subject matter with clarity and particularity. See "Manual of Patent Examining Procedures" Sections 2111, 2173.

The Nautilus Standard of "Reasonable Certainty"

The patent in Nautilus involved electrodes for monitoring human heart rate during exercise. The claim term at issue described the relative placement of electrodes "mounted ... in spaced relationship with each other." The district court found the term "in spaced relationship" to be "insolubly ambiguous" under the prior standard for claim definiteness, as defined in Exxon Research v. United States, because the claims did not specify what precisely the space should be or supply parameters for determining the appropriate space. See Biosig Instruments, Inc. v. Nautilus, Inc., 2011 WL 11745378 (S.D.N.Y Sep. 29, 2011); Exxon Research & Eng'g. Co. v. United States, 265 F.3d 1371, 1375 (Fed. Cir. 2001) (stating that a claim is indefinite if it is either not "amenable to construction" or is "insolubly ambiguous.").

The Federal Circuit reversed because the intrinsic evidence surrounding the claim term contained inherent parameters of the claimed apparatus sufficient to understand the metes and bounds of the "spaced relationship"; therefore the claims were not insolubly ambiguous. The Supreme Court granted certiorari and declared that the "insolubly ambiguous" test would "breed lower court confusion" because it lacks the precision that Section 112 demands. It is not sufficient that a court can ascribe some meaning to a patent's claims. A patent is invalid if its claims, read in light of the specification and the prosecution history, fail to inform, with reasonable certainty, a skilled artisan about the scope of the invention.

The "reasonable certainty" standard has been applied by district courts and the Federal Circuit since Nautilus, finding several patents invalid for indefiniteness. When deciding Dow v. Nova under the "insolubly ambiguous" test in August 2015, the Federal Circuit initially found the claims related to determining "a slope of strain hardening" definite, because some meaning could be ascribed to the term. Dow Chem. Co. v. Nova Chems. Corp. (Canada), 458 F. App'x 910 (Fed. Cir. 2012). However, upon reevaluating the claims under the "reasonably certainty" standard after Nautilus, the court held that the claims were indefinite because three methods existed that yielded different results, none of which were taught in the specification, and that the specification did not provide "any guidance as to which method should be used or even whether the possible universe of methods is limited to these ... methods." Dow Chem. Co. v. Nova Chems. Corp. (Canada), 803 F.3d 620, 634 (Fed. Cir. 2015).

BASF Corp. v. Johnson Matthey Inc.

More recently, the Federal Circuit added to its definiteness jurisprudence in BASF Corp. The patent in BASF Corp. concerned catalytic conversion of nitrogen oxides in an exhaust gas stream. The claims included a "material composition A" and "material composition B," each material being "effective for catalyzing" or "effective to catalyze" certain chemical reactions. The district court sided with Johnson Matthey and held that the language "effective to catalyze" and "effective for catalyzing" was indefinite because none of the claims recited a minimum level of function needed to meet this "effective" limitation or a particular measurement method to determine whether a composition is "effective" enough to fall within the claims. BASF Corp. v. Johnson Matthey Inc., 14-1204 (D. Del. Feb. 9, 2016). Thus, a skilled artisan could not determine which materials were within the "material composition A" or "material composition B" limitations.

The Federal Circuit reversed, finding that the intrinsic evidence showed that it was the arrangement of the catalysts, rather than the selection of particular catalysts, that rendered the invention novel. An inference of indefiniteness from the scope of the claims was therefore incorrect. As long as the claims provide reasonable certainty, simply claiming a product in functional terms does not mean the claims are indefinite. Moreover, the "context" provided by the intrinsic record is important when analyzing claim definiteness under the reasonable certainty standard.

Takeaways

The standard for finding claims definite has evolved from whether a court can ascribe some meaning to the claims, to whether a skilled artisan can understand the claims with reasonable certainty when read in light of the specification. Patent practitioners should avoid ambiguous claim terms that are not well understood or generally used by those skilled in the art. To ensure that claims are definite under the "reasonable certainty" standard, provide sufficient support in the specification either by explicitly defining ambiguous claim terms or by including specific, objective criteria for assessing the meaning and scope of the terms. Finally, use the language of the claims in the specification, provide examples of critical claim terms in the specification, and provide structure in the specification for functional claims.

The authors thank Darren Donnelly, Dan Brownstone and Rob Winant for their helpful comments on a previous version of this article.