A recent unanimous decision by the U.S. Supreme Court in Nautilus v. Biosig significantly increases the opportunity for a claim to be held as indefinite. In particular, the Supreme Court has set forth a new standard that provides powerful new ammunition for challenging ambiguous patent claims under 35 U.S.C. § 112, ¶ 2 and imposes a need for greater care during patent application drafting and prosecution to ensure claims satisfy this new requirement.

The technology in Nautilus related to a heart rate monitor for use with exercise equipment. The disputed claim term related to two electrodes in the heart rate monitor, which the claim required to be "in spaced relationship with each other." The district court granted summary judgment, determining that the term "spaced relationship" rendered the claim at issue indefinite. The district court concluded that the term "did not tell [the court] or anyone what precisely the space should be" or provide any parameters for determining the appropriate spacing. The federal circuit reversed based on its prior jurisprudence related to the indefiniteness standard, finding the claim at issue was not "insolubly ambiguous."

Prior to this case, the federal circuit held that patent claims would be deemed indefinite only if the terms of the claims were "insolubly ambiguous" or "not amenable to construction." This standard often proved to be a high hurdle for accused infringers and, according to the Supreme Court, "tolerate[d] some ambiguous claims but not others." The Supreme Court determined that the prior standard lacked the precision required under Section 112, ¶ 2 and created confusion among the lower courts.

Thus, the Supreme Court undertook to provide a standard that addressed the "delicate balance" between allowing enough uncertainty in claim terms to encourage inventiveness and providing clear notice of what is claimed. The Supreme Court also noted that the lack of a strong indefiniteness standard would merely encourage ambiguous patent claiming techniques. In that regard, the Supreme Court held that accused infringers need only prove that the patent claims fail to inform a person skilled in the art about the scope of the patent with reasonable certainty. As the federal circuit applied the "insolubly ambiguous" standard in determining the claim at issue in Nautilus was valid, the Supreme Court reversed and remanded for reconsideration under the newly announced standard. The Supreme Court offered no opinion on the validity of the patent claims at issue.

The new standard will likely have a strong impact on the ability of accused infringers to establish that a claim is indefinite. The lightened standard may prove particularly useful in defending claims brought by non-practicing entities that tend to assert ambiguous patent claims (particularly in the software context) in litigation and covered business method review proceedings. The new standard may also impact prosecution of patents before the U.S. Patent and Trademark Office (USPTO).