Today the U.S. Supreme Court issued its decision in Nautilus v. BioSig that adopts a “reasonable certainty” standard for determining whether a patent claim is invalid because it is indefinite, and  rejected the Federal Circuit’s “amenable to construction” and not “insolubly ambiguous” standard that had made indefiniteness challenges harder to establish.  The unanimous Supreme Court opinion, written by Justice Ginsburg, summarized its ruling as follows:

According to the Federal Circuit, a patent claim passes the §112, ¶2 threshold so long as the claim is “amenable to construction,” and the claim, as construed, is not “insolubly ambiguous.”  We concluded that the Federal Circuit’s formulation, which tolerates some ambiguous claims but not others, does not satisfy the statute’s definiteness requirement.  In place of the “insolubly ambiguous” standard, we hold 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.

The Patent-In-Suit.  The patent-in-suit concerns a heart-rate monitor used during exercise that can distinguish electrocardiagraph (ECG) signals associated with a user’s heart beat from electromyogram (EMG) signals associated with the user’s skeletal muscle movements.  Specifically, the patent takes advantage of the different measurements of ECG and EMG signals when measured from the left hand and right hand:  ECG signals measured on the left hand have the opposite polarity from  ECG signals measured on the right hand; but EMG signals have the same polarity at each hand.  In the patent, a user grips a cylindrical bar such that each hand contacts two electrodes (one “live” and one “ground”) and the measurements are used to measure the ECG signals while cancelling-out the EMG signals.  The asserted patent claim 1, among other things, required on each half of a cylindrical bar a live electrode and a common electrode “mounted … in spaced relationship with each other.”

District Court Ruling.  During claim construction, Biosig, the patent owner, argued that the term “in spaced relationship” refers to the distance between the live electrode and the common electrode in each electrode pair.  Nautilus, the patent challenger, argued that the term “spaced relationship” must be a distance “greater than the width of each electrode.”  The district court ruled that the term means “there is a defined relationship betwen 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.”

Nautilus then moved for summary judgment that the claim was invalid for being indefinite as construed.  The district court agreed, ruling that the words “did not tell [the court] or anyone what precisely the space should be,” or even supply “any parameters” for determing the appropriate spacing.

Federal Circuit.  The Federal Circuit reversed under a standard that finds indefinitness “only when [the claim] is ‘not amenable to construction’ or ‘insolubly ambiguous.'”  The Federal Circuit found inherent parameters made the claim sufficiently definite, such as the need for the electrodes to be in contact with the user’s hands and, thus, the width of spacing between electrodes cannot be greater than the width of the user’s hands.

Supreme Court.  The Supreme Court noted the parties’ agreed that definiteness is to be evaluated from the perspective of someone skilled in the relevant art at the time the patent was filed reading the claims in light of the patent’s specification and prosecution history.  The disagreement was on how much imprecision the definiteness requirement allows.  The definite requirement is a “delicate balance”.  It must take into acount the inherent limitations of langauge and that “[s]ome modicum of uncertanty … is the price of ensuring the appropriate incentives for innovation.”  On the other hand, the patent must be precise enough “to afford clear notice of what is claimed, thereby apprising the public of what is till open to them” and a loose definiteness requirement may tempt patent applicants “to inject ambiguity into their claims” even though “the patent drafter is in the best position to resolve the ambiguity.”  Thus “[t]he definiteness requirement … mandates clarity, while recognizing that absolute precision is unattainable.”

The Federal Circuit’s articulated standard provides little guidance and caused confusion in district courts.  Tolerating imprecision just short of “insolubly ambigous” would diminsh the public notice function and “foster the innovation-discouraging ‘zone of uncertainty.'”  In practice, the Federal Circuit may have applied a more rigorous standard than the terms “insoluably ambiguous” and “amenable to construction” may convey, but the standard as expressed “can leave courts and the patent bar at sea without a reliable compass.”  The Supreme Court thus reversed and remanded the case back to the Federal Circuit to consider whether the patent claims at issue are indefinite under the definiteness standard articulated by the Supreme Court.