US Supreme Court Defines Indefiniteness: Nautilus, Inc v Biosig Instruments, Inc

On June 2, 2014, the US Supreme Court (Court) released its decision in Nautilus Inc v Biosig Instruments, Inc, and has clarified the standard for definiteness under section 112, paragraph 2 of the US Patent Act. The patent at issue relates to a heart-rate monitor for use during exercise. Previous heart-rate monitors measuring electrical signals were said to be inaccurate because electromyogram (EMG) signals from skeletal muscles masked electrocardiograph (ECG) signals from heartbeats. The inventor noted that EMG signals from each hand have the same polarity, while ECG signals have opposite polarity in opposite hands. From this difference, using circuitry, the patented device filters out the ECG signals from the EMG signals. The patent claim included the element in which a live electrode and a common electrode were “mounted…in spaced relationship with each other.” Nautilus alleged that the term “spaced relationship,” as construed by the District Court, was indefinite. The District Court agreed, and dismissed the case in a summary judgment, because the words did not tell anyone “what precisely the space should be” or supply “any parameters” for determining the appropriate spacing. The Court of Appeals for the Federal Circuit (CAFC) reversed and remanded, stating that a claim is only indefinite when it is “not amenable to construction” or “insolubly ambiguous”. The parties agreed that definiteness is to be evaluated from the perspective of a person skilled in the art, and the claims are to be read in light of the specification and prosecution history. The question before the Court was how much imprecision section 112, paragraph 2 of the US Patent Act tolerates. The Court noted the “delicate balance” of the definiteness requirement. On the one hand, the requirement must take into account the inherent limitations of language; on the other hand, the patent must be precise enough to provide the public with clear notice of “what is still open to them.” Ultimately, the Court concluded that the standard to be adopted is “reasonable certainty”. The Court further stated: “It cannot be sufficient that a court can ascribe some meaning to a patent’s claims; the definiteness inquiry trains on the understanding of a skilled artisan at the time of the patent application, not that of a court viewing matters post hoc. To tolerate imprecision just short of that rendering a claim “insolubly ambiguous” would diminish the definiteness requirement’s public-notice function and foster the innovation-discouraging “zone of uncertainty,” […] against which this Court has warned.” The Court also cautioned against the CAFC’s seemingly formulaic approach rather than probative enquiry, and commented that such an approach “can leave courts and the patent bar at sea without a reliable compass.” Finding that the CAFC had invoked a standard more amorphous than the statutory requirement allowed, the Court remanded the case to be reconsidered under the proper standard. Summary by: Cheryl Cheung