Supreme Court Sets Definite Test for Patent Indefiniteness

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Nautilus Inc. isn’t the only winner in the U.S. Supreme Court case decided on June 2nd this year. The court ruled in Nautilus’ favor in a patent infringement case that has broad implications. With the evolution of technology over the years, it had become very crucial to decide what would be definite and obvious to a person skilled in the art at the time of invention. The Nautilus test, as penned by the Supreme Court, states that:

A patent is invalid for indefiniteness if its claims, read in light of the patent’s specification and prosecution history, fail to inform, with reasonable certainty, those skilled in the art about the scope of the invention.

Practitioners should be aware that the courts will now look through a new lens to determine definiteness. The Nautilus test for definiteness focuses on the perspective of one skilled in the art at the time of application to determine whether there is sufficient teaching in the patent description and the prosecution history to reasonably inform those skilled in the art about the scope of the invention. The Nautilus test was clearly concerned about preventing patent drafters from intentionally including ambiguity into claims to broaden the scope of the invention. Claim amendments performed during prosecution would play a crucial role in nailing down the invention precisely. Thus, patent applicants should carefully consider the Nautilus test when choosing claim language to define their inventions.

Nautilus thus strengthens the ability of alleged infringers to prevail on indefiniteness defenses against patent claims. The Nautilus test would enable defendants in patent litigations to argue on patent validity with certainty and conviction. If the prosecution history and patent specification doesn’t clearly describe any patented claim term, the patent would be liable to be invalidated. The interpretation of the claim terms would no longer be at the mercy of the language limitation. The absolute precise interpretation of the claims would allow the defendants to distinguish the patented invention from their accused product/process.

Case Background

Under 35 U.S.C. § 112 ¶ 2, patent claims must “particularly point out and distinctly claim the subject matter which the inventor or a joint inventor regards as the invention.” This is referred to as the “definiteness” standard. A claim that fails to satisfy the definiteness standard is invalid and may not be enforced. Since years, Federal Circuit has held that claims are indefinite under § 112 ¶ 2 when they are “not amenable to construction” or are “insolubly ambiguous.”

In 2013, the Federal Circuit applied this standard in the case of Biosig Instruments, Inc. v. Nautilus, Inc.  The claim at issue in the case concerned a heart rate monitor for exercise equipment that used two electrodes in a “spaced relationship” with each other. In prior ex parte reexamination proceedings, the patent owner argued that the “spaced relationship” was a key limitation that distinguished the claimed invention from dual-electrode monitors found in the prior art. In the District Court proceedings, however, the patent owner argued that a “spaced relationship” could be any “defined relationship” between the electrodes. Based on that construction, the U.S. District Court for the Southern District of New York found that the “spaced relationship” limitation was indefinite under § 112 ¶ 2 because it would not disclose the bounds of the claimed invention to someone of skill in the art. The Federal Circuit reversed, holding that it was possible to assign a meaning to “spaced relationship” and therefore the limitation was not indefinite. In particular, the Federal Circuit held that the “spaced relationship” would necessarily be close enough so that the electrodes could fit within a person’s hand. The Federal Circuit also noted that a person of skill in the art could perform testing to determine the ideal spaced relationship.

The Landmark Decision

Upon Nautilus’s petition, the case was taken up by the Supreme Court to set defined criteria for ascertaining patent claim indefiniteness. In a unanimous decision delivered by Justice Ginsburg, the Supreme Court rejected the “insolubly ambiguous” and “amenable to construction” tests that the Federal Circuit applied in Biosig. The Court noted that those standards “lack the precision that § 112 ¶ 2 demands” and therefore “can breed lower court confusion.” The Court held that § 112 ¶ 2 requires that:

“a patent’s claims, viewed in light of the specification and prosecution history, inform those skilled in the art about the scope of the invention with reasonable certainty.” 

The Court noted that this standard “mandates clarity, while recognizing that absolute precision is unattainable.”

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Aditi Das
Aditi Das

Aditi Das is a compulsive sci-fi dreamer who conjures up aliens from vehicles stuck in a traffic snarl. When she isn’t driving teams, inspiring them to shred technologies to pieces and unearth their DNA, she’s busy dishing up Bengali food and blogging.


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