Supreme Court Rules Patent Claim Language Must Have ‘Reasonable Certainty’

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 in spaced 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...