The question of how ambiguous a patent claim can be before it is considered invalid will be argued before the US Supreme Court this week in the case of Nautilus Inc. v. Biosig Instruments Inc.
Patent law requires the language of the claims be clear and distinct. But some patent attorneys deliberately use ambiguous language. If the claims have some ambiguity, there is room to argue later that they cover a wide range of technologies.
In this case, US 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.
Claim language related to this diagram from a patent is in question in the case before the Supreme Court.
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 language that gave rise to the dispute. The original 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.”
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. If you abdicate your role, arcane legalese runs the risk of creating a patent that is invalid.
— Daniel Forman is a partner at law firm Goodwin Procter LLP and a former software engineer.