In Nautilus, Inc. v. Biosig Instruments, Inc.Appeal No. 13-169, the Supreme Court vacated and remanded Federal Circuit’s reversal of summary judgment because the Federal Circuit’s definiteness standard was too lenient.

Biosig filed a patent infringement suit claiming Nautilus’ exercise machines infringed its patent. Biosig’s patent claims a heart rate monitor that includes a “live” electrode and “common” electrode “mounted . . . in spaced relationship with each other.” The district court granted Nautilus’ motion for summary judgment on the basis the claim term “in spaced relationship with each other” failed the definiteness requirement of 35 U.S.C. § 112, second paragraph.  The Federal Circuit reversed and remanded, finding a patent claim meets the definiteness threshold so long as the claim is “amenable to construction” and the claim is not “insolubly ambiguous.” 

The Supreme Court held the Federal Circuit’s test does not satisfy the statute’s definiteness requirement and can leave courts without a reliable compass. The Court held a patent is invalid for indefiniteness if its claims, read in light of the specification and the prosecution history, fail to inform, with reasonable certainty, those skilled in the art about the scope of the invention. The Court emphasized this standard not only takes into account the inherent limitations of language, but also requires a patent must be precise enough to afford clear notice of what is claimed. The Court vacated and remanded to the Federal Circuit for reconsideration under the proper standard.