In a unanimous ruling issued on June 2nd, the Supreme Court in Nautilus, Inc. v. Biosig Instruments, Inc. (U.S., No. 13-369) vacated and remanded a Federal Circuit decision concerning the Patent Act’s definiteness requirement. Section 112 of the Patent Act requires that a patent “particularly point[] out and distinctly claim[]” the subject matter of a patent to define the boundaries of the invention and its protected subject matter. In Nautilus, the Supreme Court rejected the Federal Circuit’s test that a patent claim is indefinite only if it is “insolubly ambiguous” and not “amenable to construction.” Instead, the Court articulated the indefiniteness test as whether a patent’s 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.” Thus, if a claim’s scope cannot be ascertained with “reasonable certainty” by one of ordinary skill in the art from the patent’s specification and prosecution history, the claim is invalid as indefinite under § 112.

In Nautilus, Justice Ginsburg, who authored the opinion, noted the “delicate balance” between the “inherent limitations of language” and the mandate of § 112, conceding that there may always be “[s]ome modicum of uncertainty” surrounding the breadth of a patent’s subject matter. But Justice Ginsburg emphasized that the description of a patent’s scope “must be precise enough to afford clear notice of what is claimed” to eliminate the “zone of uncertainty which enterprise and experimentation may enter only at the risk of infringement claims.”

In clarifying the definiteness standard, the Court addressed concerns voiced by both parties in Nautilus, as well as the numerous amici who submitted briefs, that the Federal Circuit’s “insolubly ambiguous”/“amenable to construction” standard allowed more ambiguity and imprecision than § 112 permits. By allowing ambiguity in a claim only to the extent the claim is not “insolubly ambiguous,” the Federal Circuit’s standard “diminish[ed] the definiteness requirement’s public notice function.” The Court recognized that the Federal Circuit’s standard often left courts and the patent bar “at sea without a reliable compass.” The Court ultimately declined to apply its refined definiteness standard to the technology at issue in the case and remanded the case back to the Federal Circuit.