A patent must be “definite”: it must particularly point out and distinctly claim the invention. 35 U.S.C. § 112 ¶ 2. Otherwise, the patent is not valid. 35 U.S.C. § 282 ¶ 2(3). On June 2, 2014, the Supreme Court in Nautilus v. Biosig Instruments unanimously decided the appropriate standard for determining whether a patent claim is definite, rejecting the Federal Circuit’s standard.
Biosig owns U.S. Patent No. 5,337,753 for an exercise heart-rate monitor of the kind on a cylindrical treadmill grip, where the user grips two sets of sensors, one with each hand. Each set of sensors has two electrodes “in a spaced relationship with each other,” according to the patent claims. The district court found this phrase to be indefinite, rendering the claims invalid. But the Federal Circuit reversed, applying its definiteness standard, finding the phrase was neither “insolubly ambiguous” nor “not amenable to construction.”
The Supreme Court surveyed the history of the Patent Act, finding the definiteness requirement has been “largely unaltered” since 1870. Definiteness requires a “delicate balance” between the “inherent limitations of language” and affording “clear notice” of what the invention is; definiteness “mandates clarity, while recognizing that absolute precision is unattainable.” Because the Federal Circuit’s standard would “tolerate imprecision” for claims falling just short of being insolubly ambiguous, that standard “lacked the precision” § 112 ¶ 2 demands.
Reversing the Federal Circuit, the Supreme Court held the proper standard for definiteness finds a patent invalid if the claims “fail to inform, with reasonable certainty, those skilled in the art about the scope of the invention.” The issue presented to the Court was purely a legal one—the proper standard for definiteness—so the Court did not address whether the clear and convincing evidentiary burden applies. The Court remanded to the Federal Circuit to determine whether Biosig’s claims are indefinite under the appropriate standard.
The Supreme Court found it relevant that vague patent claims breed uncertainty among competitors, and that “absent a meaningful definiteness check…patent applicants face powerful incentives to inject ambiguity into their claims.” Nautilus is the Court’s effort to “[eliminate] that temptation.”