Supreme Court restates the test for determining ‘definiteness’ of patent application

by Charles Miller

Our patent laws reward inventors with a limited monopoly but require that such a monopoly be defined with clear boundaries. A patent application must describe the invention with a certain degree of “definiteness.”

When Congress enacted the first Patent Act in 1790, it required patent grantees to submit a written specification “containing a description … of the thing or things … invented or discovered,” which “shall be so particular” as to “distinguish the invention or discovery from other things before known and used.” Act of Apr. 10, 1790, § 2, 1 Stat. 110. The 1870 Act’s definiteness requirement remains largely unaltered. Section 112 of the Patent Act requires the patent applicant to conclude the specification with “one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention.” 35 U.S.C. § 112, ¶ 2 (2006 ed.). A lack of definiteness renders invalid “the patent or any claim in suit.” § 282, ¶ 2(3).

The Supreme Court has now concluded that the Federal Circuit’s standard for evaluating definiteness was itself too indefinite. Nautilus, Inc. v. Biosig Instruments, Inc., 134 S.Ct. 2120 (2014). Under the Federal Circuit’s approach, a patent claim failed to meet the definiteness requirement only when it is “not amenable to construction” or “insolubly ambiguous.” The Supreme Court rejected those formulations because they can “breed lower court confusion, for they lack the precision § 112, ¶ 2 demands.” Id., at 2130.

It cannot be sufficient 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. To tolerate imprecision just short of that rendering a claim “insolubly ambiguous” would diminish the definiteness requirement’s public-notice function and foster the innovation-discouraging “zone of uncertainty,” […] against which this Court has warned.


The Supreme Court held that, to satisfy the definiteness requirement of § 112, ¶ 2, a patent’s claim must, “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., at 2129 (emphasis added). The standard emphasizes that definiteness is to be evaluated from the perspective of someone skilled in the relevant art at the time of the application (not lawyers or judges or the general public, and not from some point later in time). Further, in assessing definiteness, claims are to be read in light of that patent’s specification and prosecution history. The court noted that a “patent must be precise enough to afford clear notice of what is claimed, thereby ‘appris[ing] the public of what is still open to them.’” Id.

By vacating and remanding the case before it, the Supreme Court left no doubt that it found the Federal Circuit’s prior standard to be too generous. However, the Supreme Court provided very little guidance as to just how to apply its “reasonable certainty” standard. Indeed, Court “decline[d] to apply the standard we have announced to the controversy” before it and instead remanded the case to the Federal Circuit. Precisely how that court will apply the new standard remains to be seen.

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by Charles Miller

Charles Miller is a licensed attorney and a partner at Heygood, Orr & Pearson. Charles focuses his practice on areas of complex commercial litigation and personal injury litigation.