On June 2, 2014, in Nautilus, Inc., v. Biosig Instruments, Inc. (Nautilus), the US Supreme Court unanimously overturned the existing Federal Circuit standard for invalidating a patent claim as indefinite. Nautilus, Inc., v. Biosig Instruments, Inc., 572 U.S. ____, Slip Opinion No. 13–369, (2014). In place of the “insolubly ambiguous” standard, the Court held that “a patent is invalid for indefiniteness if its 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.”1

For a patent claim to be definite, the “specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention.”2 The lack of definiteness renders a patent claim invalid and indefiniteness is a common affirmative defense against a claim for patent infringement.3

In 2004, Biosig Instruments, Inc. (Biosig) brought a patent infringement suit in the US District Court of the Southern District for New York against Nautilus asserting US Patent No. 5,337,753 (the ‘753 Patent). The ‘753 Patent describes and claims a grip-activated heart rate monitor, used with exercise equipment, that eliminates noise signals caused by muscle movement. The relevant limitations of asserted Claim 1 are provided below:

Claim 1:

a first live electrode and a first common electrode mounted on said first half inspaced relationship with each other;

a second live electrode and a second common electrode mounted on said second half in spaced relationship with each other;

In 2011, the District Court held a claim construction hearing to determine the proper construction of the claim term “spaced relationship” and determined “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,” but made no reference to the width of the electrodes.4 Thereafter, Nautilus filed a motion for summary judgment on the ground that the claim term “spaced relationship” as construed was indefinite under § 112, ¶2. Even thought the District Court construed the claim term, the record reflected ambiguity with respect to the meaning of the term. Therefore, the District Court granted the Nautilus’ motion for summary judgment and concluded that the term “spaced relationship” was indefinite as a matter of law.

Biosig appealed the District Court’s decision to the Federal Circuit and argued that the claim term “spaced relationship,” when read in light of the specification and associated drawings, delineates the scope of the claim with sufficient precision. Nautilus argued that the claim term“spaced relationship” is open to multiple configurations. Under the previous standard, the Federal Circuit considers the definiteness requirement of § 112, ¶2 satisfied if a claim is “amenable to construction,” and the claim, as construed, is not “insolubly ambiguous.”5 The Federal Circuit used the “insolubly ambiguous” standard and found the claims of the ‘753 Patent definite in view of the “intrinsic evidence” (i.e., the claim language, the specification, and the prosecution history) and “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

On petition to the Supreme Court by Nautilus, the Supreme Court determined that the Federal Circuit’s “formulations can breed lower court confusion, for they lack the precision §112, ¶2 demands.”7 “In place of the ‘insolubly ambiguous’ standard, the Supreme Court held ‘that a patent is invalid for indefiniteness if its 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.’”8 The Supreme Court reasoned that the previous standard “would diminish the definiteness requirement’s public-notice function and foster the innovation-discouraging ‘zone of uncertainty,’ United Carbon, 317 U.S., at 236, against which this Court has warned.”9 The Federal Circuit’s judgment was vacated and the case was remanded for further proceedings consistent with the Supreme Court’s “reasonable certainty” standard for determining definiteness.

It remains to be seen how the Supreme Court’s decision will impact invalidity arguments on indefiniteness and whether courts will see an increase in indefiniteness arguments in view of the Supreme Court’s revised standard. Also, to avoid indefiniteness issues at the United States Patent and Trademark Office (USPTO), patent practitioners drafting applications will want to pay careful attention to claim language which may have degrees of meaning and could be subject to multiple interpretations. Patent attorneys should undertake an analysis of whether such claim language is “reasonably certain” in view of the specification and arguments made in the file history to avoid indefiniteness rejections and prosecution history estoppel issues.