Nautilus, Inc. v. Biosig Instruments, Inc

Background

A patent owner, Biosig Instruments, sued a company that sold exercise machines, Nautilus, alleging use of Biosig’s heart‑rate monitor technology without a license. The disputed patent describes a hollow cylindrical bar a user grips with both hands. Each half of the bar has two electrodes — a “live” and a “common” electrode — and electronics that subtract muscle signals (EMG) to isolate the heart’s electrical signal (ECG). The key claim phrase at issue is that the two electrodes are “mounted … in spaced relationship with each other.” The District Court found that phrase indefinite and entered summary judgment for Nautilus. The Federal Circuit reversed, saying a claim is valid if it is “amenable to construction” and not “insolubly ambiguous.”

Reasoning

The Supreme Court rejected the Federal Circuit’s test. It held that a patent claim is invalid if, when read with the patent’s specification and the record of the patent application, it fails to inform skilled experts with reasonable certainty about the invention’s scope. The Court emphasized that some imprecision is inevitable but that claims must give clear notice to competitors and avoid a “zone of uncertainty.” The Court also explained that the language must be judged from the perspective of a skilled person at the time of filing.

Real world impact

The decision requires lower courts to re‑evaluate patents under the new “reasonable certainty” standard. Patent drafters will face stronger incentives to use precise claim language. The Court did not decide whether the heart‑rate monitor patent is valid on the merits; it vacated the Federal Circuit’s judgment and remanded for reconsideration under the proper standard.

Dissents or concurrances

A Federal Circuit judge concurred in the result but used a narrower analysis, declining to tie the “spaced relationship” phrase directly to the device’s function of removing EMG.