In Nautilus, Inc. v. Biosig Instruments, Inc., No. 13-369, slip op., 2014 WL 2440536, __ U.S. __ (June 2, 2014), the Supreme Court rejected the Federal Circuit’s “insolubly ambiguous” standard for determining compliance with the definiteness requirement of 35 U.S.C. § 112 and held that “a patent is invalid for indefiniteness if its claims, read in light of the specification delineating the patent, and the prosecution history, fail to inform, with reasonable certainty, those skilled in the art about the scope of the invention.” The Court vacated and remanded the case back to the Federal Circuit to consider whether the patent claims at issue are indefinite under the new standard articulated by the Court.

Biosig Instruments accused Nautilus of infringing its patented technology for monitors which are built into fitness machines, such as treadmills, that register electrical waves to estimate a user’s heart rate. At issue was the meaning of the term “in spaced relation” defining the spatial relationship between two electrodes. The U.S. District Court for the Southern District of New York construed the term to mean “there is a defined relationship between the live electrode and the common electrode…” and then granted summary judgment that the term, as construed, was indefinite because it “did not tell [the court] or anyone what precisely the space should be” or supply “any parameters” for determining the appropriate spacing.

The Federal Circuit reversed, citing prior case law that a claim is indefinite only when it is “not amenable to construction” or is “insolubly ambiguous.” See, e.g., Datamize, LLC v. Plumtree Software, Inc., 417 F.3d 1342, 1347 (Fed. Cir. 2005). The Supreme Court granted certiorari on January 10, 2014.

The definiteness requirement of 35 U.S.C. § 112(b), formerly § 112 ¶2, requires that the patent’s “specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention.” Failure to meet this requirement, i.e., that a claim is indefinite, renders that claim invalid.

The Supreme Court recognized that the indefiniteness inquiry entails a “delicate balance” between, on the one hand, taking into account the inherent limitations of language and, on the other, being precise enough to afford clear notice of what is claimed. The Supreme Court even cited the possibility of gaming the system by “patent applicants [who] face powerful incentives to inject ambiguity into their claims.” Nautilus, slip op., at 5. Elimination of this temptation, the Supreme Court said, “is in order, and the patent drafter is in the best position to resolve the ambiguity in … patent claims.” Id. (citations omitted).

Accordingly, the Supreme Court held that the “insolubly ambiguous” standard, “which tolerates some ambiguous claims but not others, does not satisfy the statute’s definiteness requirement.” The claim language must “apprise the public of what is still open to them” or, otherwise, there would be a “zone of uncertainty which enterprise and experimentation may enter only at the risk of infringement.” Nautlius, slip op. at 10 (citations omitted). Thus, the Supreme Court’s formulation of the definiteness standard “require[s] that a patent’s claims, viewed in light of the specification and prosecution history, inform those skilled in the art about the scope of the invention with reasonable certainty.” Id.