Ambiguity inherent in functional claim terms may be resolved as to make the claim definite where a patent provides general guidelines and examples sufficient to enable a person of ordinary skill in the art to determine the scope of the claims, and definiteness does not require that a potential infringer be able to determine in advance if a particular act infringes the claims.
The Federal Circuit recently vacated and remanded a district court’s grant of summary judgment invalidating patent claims owned by Nevro Corporation (Nevro). See Nevro Corp. v. Boston Sci. Corp., Nos. 2018-2220, 2018-2349, 2020 U.S. App. LEXIS 11170 (Fed. Cir. Apr. 9, 2020) (Before Moore, Taranto, and Chen, Circuit Judges) (Opinion for the Court, Moore, Circuit Judge).
Nevro sued Boston Scientific Corporation (Boston Scientific) alleging infringement of eighteen claims across seven patents. The patents at issue were directed to high-frequency spinal cord stimulation therapy to inhibit pain without producing sensations such as tingling or paresthesia found in prior conventional techniques. The district court granted summary judgment in favor of Boston Scientific, holding twelve of the asserted claims invalid and granting non-infringement of the remaining six. Nevro appealed the district court’s judgment of invalidity, and Boston Scientific cross-appealed the district court’s finding that the six non-infringed claims were not indefinite.
In overruling the district court’s findings of invalidity, the Federal Circuit first looked at a number of claims directed to “paresthesia-free” embodiments where therapy-induced paresthesia was not a prerequisite to achieving pain reduction. The district court determined that “paresthesia-free” meant that the therapy did not produce sensations like tingling, pins and needles, or numbness, and that the term did not render the asserted method claims indefinite; the Federal Circuit agreed with this conclusion. However, the district court found the “paresthesia-free” system and device claims to be indefinite because “infringement of these claims depended on the effect of the system on a patient, and not a parameter of the system or device itself.” Using this reasoning, the district court concluded that a skilled artisan could not identify the bounds of the system and device claims with reasonable certainty.
The Federal Circuit disagreed. The Court noted that “[t]he test for indefiniteness is not whether infringement of the claim must be determined on a case-by-case basis. Instead, it is simply whether a claim ‘inform[s] those skilled in the art about the scope of the invention with reasonable certainty.’” Although “paresthesia-free” was a functional term, ambiguity inherent in functional terms may be resolved where a patent provides general guidelines and examples sufficient to enable a person of ordinary skill in the art to determine the scope of the claims.
The Court found that the asserted claims recited sufficient parameters for a system or device configured to generate a “paresthesia-free” signal. The relevant patent specifications taught how to generate and deliver the claimed signals using the recited parameters, so a person of ordinary skill in the art would have been able to determine the scope of the claims. Therefore, the patents provided reasonable certainty about the scope of the asserted claims by giving detailed guidance and examples “of systems and devices that generate and deliver paresthesia-free signals with high frequency, low amplitude, and other parameters.” The Court also found the fact “[t]hat a given signal will eliminate paresthesia in some patients, but not others, does not render the claims indefinite.”
Boston Scientific argued that the claims were indefinite because, in its view, infringement of the claims could be determined only after using the device or performing the method. However, the Court disagreed, stating that definiteness did not require “that a potential infringer be able to determine ex ante if a particular act infringes the claims.”
The Court also examined a set of claims reciting a “signal generator configured to generate” a therapy signal with set parameters. The district court held that “configured to” rendered the claims indefinite, as it was susceptible to differing constructions. However, the district court applied an incorrect legal standard in finding the claims indefinite. “The test for indefiniteness is whether the 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 Federal Circuit reiterated that the test is not merely whether a claim is susceptible to differing interpretations. Applying this standard, the Court determined that “configured to” did not render the claims at issue indefinite because a person of ordinary skill in the art would be reasonably certain of the meaning of “configured to” based on the claims and specifications of the asserted patents.
A handful of asserted claims also recited a “means for generating” a paresthesia-free therapy signal. The district court found that the specifications of the asserted patent did not adequately disclose a corresponding structure for this means plus function language, and sua sponte held the claims indefinite. The Federal Circuit disagreed, finding that the specification clearly recited a pulse generator, not a general computer or processor, as the structure for the “generating” function.
The last subset of claims considered by the Court recited a “therapy signal,” which the district court construed as an “electrical impulse” or “electrical signal.” Nevro challenged the district court’s construction on appeal, and Boston Scientific contended that the district court erred in not holding that “therapy signal” rendered the asserted claims indefinite. The Federal Circuit found that although the district court had erred in its construction, it correctly had determined that the claims reciting a “therapy signal” were not indefinite. Ultimately, the Federal Circuit vacated and remanded the district court’s judgment of invalidity with respect to all twelve claims asserted by Nevro on appeal.