Supreme Court Adopts Reasonable Certainty Test for Definiteness


On June 2, 2014, the Supreme Court issued a unanimous decision in Nautilus, Inc. v. Biosig Instruments, Inc., rejecting the Federal Circuit’s “insolubly ambiguous” test for patent claim indefiniteness under 35 USC § 112, and instead adopting a “reasonable certainty test.” The Court vacated the Federal Circuit decision rendered under the “insolubly ambiguous” test, and remanded for the Federal Circuit to evaluate Biosig’s claims under the new standard.

The Patent at Issue

The patent at issue was Biosig’s U.S. Patent 5,337,753, directed to a heart rate monitor associated with an exercise apparatus and/or exercise procedures. At issue was claim language regarding a “spaced relationship” between electrodes positioned on an “elongate member” that is held by the user to obtain a heart rate measurement. (Please see this article for a more detailed discussion of this case.)

The Prior Proceedings

The district court construed the term “spaced relationship” to mean that “there is a defined relationship between the live electrode and the common electrode on one side of the cylindrical bar and the same or a different defined relationship between the live electrode and the common electrode on the other side of the cylindrical bar,” and held the term indefinite because it “did not tell me or anyone what precisely the space should be . . . . Not even any parameters as to what the space should be . . . . Nor whether the spaced relationship on the left side should be the same as the spaced relationship on the right side.”

The Federal Circuit reversed, applying an “insolubly ambiguous” test that would hold a claim indefinite only if it is “not amenable to construction.” With reference to the claim language at issue, the court stated:

When a “word of degree” is used, the court must determine whether the patent provides “some standard for measuring that degree.” …. Similarly, when a claim limitation is defined in “purely functional terms,” a determination of whether the limitation is sufficiently definite is “highly dependent on context (e.g., the disclosure in the specification and the knowledge of a person of ordinary skill in the relevant art . . . ).”

The court determined that the “claim language, specification, and … figures” of the ‘753 patent “provide sufficient clarity to skilled artisans as to the bounds of this disputed term.”

The Supreme Court Decision

The Supreme Court decision recognizes that the standard for indefiniteness must balance two competing interests: permitting “[s]ome modicum of uncertainty” to provide “appropriate incentives for innovation” while requiring enough precision “to afford clear notice of what is claimed” and disincentivize the deliberate creation of “zone[s] of uncertainty” around claim scope. The Court determined that these interests are best balanced when the statute is read “to require 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.”

Although the Court took some time to explain the questions presented by the claims at issue, it refused to apply the new “reasonable certainty” test in the first instance, instead remanding to the Federal Circuit. Thus, it will be up to the Federal Circuit in the first instance to determine how to assess whether Biosig’s claims define its invention with “reasonable certainty”.

Unreasonable Uncertainty

Although the Supreme Court calls for “reasonable certainty” in claim language, its decision leaves a “zone of uncertainty” around what is required to satisfy § 112. By pronouncing a new test without applying it to the claims at issue, the Court does little more than discredit the Federal Circuit’s approach without providing even a “modicum” of guidance on the correct standard.

View This Blog


DISCLAIMER: Because of the generality of this update, the information provided herein may not be applicable in all situations and should not be acted upon without specific legal advice based on particular situations.

© Foley & Lardner LLP | Attorney Advertising

Written by:


Foley & Lardner LLP on:

Readers' Choice 2017
Reporters on Deadline

"My best business intelligence, in one easy email…"

Your first step to building a free, personalized, morning email brief covering pertinent authors and topics on JD Supra:

Sign up to create your digest using LinkedIn*

*By using the service, you signify your acceptance of JD Supra's Privacy Policy.

Already signed up? Log in here

*With LinkedIn, you don't need to create a separate login to manage your free JD Supra account, and we can make suggestions based on your needs and interests. We will not post anything on LinkedIn in your name. Or, sign up using your email address.