In a decision issued on June 2, 2014, the Supreme Court in Nautilus, Inc. v. Biosig Instruments, Inc., 572 U.S. ___ (2014), significantly changed the standard for determining whether a patent claim is sufficiently definite under 35 U.S.C § 112.

Before the Court's decision, the Federal Circuit held patent claims sufficiently definite under § 112 where the claims were "amenable to construction" and not "insolubly ambiguous." Under the new standard articulated by the Supreme Court in Nautilus, patent claims are sufficiently definite if the 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."

Definiteness of Patent Claims

Under 35 U.S.C. § 112(b), a patent must contain claims "particularly pointing out and distinctly claiming" the subject matter of the invention.1 Patent claims that fail these particularity and distinctness requirements are invalid for indefiniteness.

Under prior Federal Circuit precedent, invalidating a claim for indefiniteness was exceedingly difficult. Although the Federal Circuit had articulated the indefiniteness standard in various ways, the inquiry was generally focused on whether a claim was susceptible to any plausible construction. For example, the Federal Circuit had previously explained that a claim was not indefinite unless it was "insolubly ambiguous" and "not amenable to construction."2

As part of its increased focus on patent cases, the Supreme Court granted review in Nautilus to reconsider the Federal Circuit's standard for indefiniteness. The Court unanimously concluded that the Federal Circuit's indefiniteness standard was too forgiving of patentees. A standard focusing on whether claims are "amenable to construction" and not "insolubly ambiguous," the Court found, would diminish the definiteness requirement's public-notice function and foster an "innovation-discouraging 'zone of uncertainty.'"3

The Biosig Patent

The patent at issue in Nautilus was directed to a heart-rate monitor used with exercise equipment. The claim required, among other elements, two electrodes "mounted . . . in a spaced relationship with each other."4 The district court, on summary judgment, found the claim indefinite because it "did not tell [the court] or anyone what precisely the space should be," or even supply "any parameters" for determining the appropriate spacing.

On appeal, the Federal Circuit reversed and remanded, finding the claim valid and sufficiently definite.5 Considering the patent and other intrinsic evidence, the court discerned "certain inherent parameters of the claimed apparatus, which to a skilled artisan may be sufficient to understand the metes and bounds of 'spaced relationship.'"6

A New Definiteness Standard

The Supreme Court vacated the Federal Circuit's decision and articulated a new standard for indefiniteness under 35 U.S.C. § 112. In ascertaining the appropriate standard, the Court acknowledged the delicate balance between a necessary "modicum of uncertainty" and the precision necessary "to afford [the public] clear notice of what is claimed."7 The Court described the need for "a meaningful definiteness check" to counter what otherwise might be "powerful incentives to inject ambiguity into [a patent's] claims."8

In rejecting the Federal Circuit's standard for indefiniteness, the Court emphasized that the definiteness requirement of § 112 properly focuses not on claim construction, but on the understanding of a person of ordinary skill in the art at the time of a patent application. "It cannot be sufficient," the Court said, "that a court can ascribe some meaning to a patent's claims; the definiteness inquiry trains on the understanding of a skilled artisan at the time of the patent application, not that of a court viewing matters post hoc."9 Considering the competing concerns, the Court held that the definiteness requirement of § 112 requires "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."10

The Court vacated and remanded the case for the Federal Circuit to reassess definiteness under the new standard.

Looking Forward

By its ruling, the Supreme Court both lowered the bar for indefiniteness, and also appeared to broaden the relevant considerations to include evidence of how an ordinarily skilled artisan, at the time of filing, would understand a patent's claims. While the Supreme Court's decision did not disturb the settled rule that claim definiteness is ultimately a question of law for the court to decide,11 the decision appears to open the door for an increased role for experts in definiteness determinations.