Inventors Take Note: Supreme Court to Decide How Ambiguous is Too Ambiguous for Patents


The first time you laid eyes on a patent claim, your reaction was probably something like “what the heck does that mean?” Your second reaction was probably “who would write something like that, and why?”

Claims are written using abstruse language for a number of reasons. Most importantly, an inventor is entitled to claim his or her invention in the broadest sense that is still novel and not “obvious.” Inventors often think of their invention in the specific technical terms in which they first conceived or built it. For example, the inventor may describe the invention as using a particular circuit. It is the patent attorney’s job to make certain that the patent is not unnecessarily limited to implementations that use that particular circuit. The impulse to avoid narrow claiming leads the patent attorney to use language like “an encryption module” or “lookup means” instead of a more specific hardware or software description.

While U.S. patent law requires the language of the claims to be clear and distinct, language is inherently imprecise. There may also be occasions where some attorneys deliberately use unclear or ambiguous language. If the claims have some ambiguity, there is room to argue later that they cover a wider range of technologies than the attorney thought to describe when the claim was drafted. Ambiguity also increases the risk of trying to design around a patent, and ultimately of defending a product from a claim of infringement. By increasing risk, the attorney increases the settlement value of the patent when it is asserted.

This brings us to the question the U.S. Supreme Court will answer in Nautilus, Inc. v. Biosig Instruments, Inc., a case that was argued on April 28, 2014. In effect, the Supreme Court is being asked to decide the question “how ambiguous can a patent claim be before it is invalid?”

U.S. Patent No. 5,337,753, which is owned by Biosig Instruments, describes a heart rate monitor for use with exercise equipment. Figure 1 of the patent shows an arrangement of electrodes, numbered 9, 11, 13 and 15. Electrodes 11 and 15 are grounded.

Heart Rate MonitorThe device works on the principle that noise and electromyogram signals generated by both hands are approximately equal in amplitude and phase, whereas the electrocardiogram signals generated by both hands have opposite phase. Subtracting the signals from the “live electrodes” 9 and 13, amplifies the ECG signals and eliminates noise and EMG signals.

Claim 1 of the ’753 patent requires pairs of electrodes (e.g., 9 and 11) “in spaced relationship with each other,” and it is this “spaced relationship” language that gave rise to the dispute. The trial court decided that the claim language “did not tell me or anyone what precisely the space should be. * * * not even any parameters as to what the space should be.” The Court of Appeals for the Federal Circuit disagreed. According to the Federal Circuit, a claim is invalid for “indefiniteness” “only when it is ‘not amenable to construction’ or ‘insolubly ambiguous’,” such that “reasonable efforts at claim construction result in a definition that does not provide sufficient particularity and clarity to inform skilled artisans of the bounds of the claim.” The Federal Circuit looked at the claim language, which says the user’s hands must contact the electrodes, the drawings and the specification, and concluded that the space cannot be so small that the live and common electrodes “effectively merg[e] . . . into a single electrode with one detection point” and “cannot be greater than the width of a user’s hands.”

Not surprisingly, Nautilus and Biosig characterize the dispute quite differently. Nautilus attacks the Federal Circuit’s “insolubly ambiguous” language, arguing that it allows too much ambiguity, and creates an incentive to “draft some ambiguous claims in the hope of creating a de facto penumbra enlarging the patentee’s monopoly beyond its invention.” Nautilus asks the Supreme Court to rule that claims may not be ambiguous at all, and may not be “susceptible of multiple reasonable interpretations.” Biosig argues that the Federal Circuit’s “insolubly ambiguous” language is just short-hand for the court’s actual analysis, which invalidates claims when “reasonable efforts at claim construction result in a definition that does not provide sufficient particularity and clarity to inform skilled artisans of the bounds of the claim.” Biosig insists that a claim may be valid even though reasonable persons disagree about its interpretation. The United States filed a friend of the court brief coming down somewhere in the middle.

Regardless of how the Supreme Court rules, this case highlights the need for inventors to pay close attention to the language their patent attorneys use to claim their inventions. The attorney’s goal of avoiding unnecessary narrowing language is laudable, but the inventor may be in a better position to suggest general language that will still have clear meaning to others in the field. As an inventor, have in mind the difference between describing a concept generally and describing it ambiguously. Your goal should be to help your attorney draft general, but unambiguous, claims. Abdicating your role, arcane legalese runs the risk of creating a patent that is invalid.

IRS Circular 230 Disclosure: To ensure compliance with requirements imposed by the IRS, we inform you that any U.S. tax advice contained in this informational piece (including any attachments) is not intended or written to be used, and may not be used, for the purpose of (i) avoiding penalties under the Internal Revenue Code or (ii) promoting, marketing or recommending to another party any transaction or matter addressed herein.


DISCLAIMER: Because of the generality of this update, the information provided herein may not be applicable in all situations and should not be acted upon without specific legal advice based on particular situations.

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