In a case involving claims with functional language and means-plus-function limitations, the US Court of Appeals for the Federal Circuit found that the district court erred in its determination that three claim terms were indefinite, but agreed with the district court that a fourth term was not indefinite. Nevro Corp. v. Boston Sci. Corp., Case Nos. 18-2220; -2349 (Fed. Cir. Apr. 9, 2020) (Moore, J.).

Nevro owns patents for improved technologies for high-frequency spinal cord stimulation therapy to alleviate pain, while avoiding side effects associated with conventional stimulation therapies. Several of the asserted claims recite systems and devices in which the stimulation therapy signals are “paresthesia-free,” meaning they do not cause a tingling, pins-and-needles sensation. The district court found the claimed “paresthesia-free” systems and devices to be indefinite because infringement of the claim depends on the effect of the system on the patient, so a skilled person cannot understand the metes and bounds of the claim with reasonable certainty. Nevro appealed.

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