Functional Claim Language Not Indefinite Says Federal Circuit: Nevro Corp. v. Boston Scientific Corp.

Four functional patent claim terms were not indefinite under 35 U.S.C. § 112 and Nautilus, Inc. v. Biosign Instruments, Inc. (S. Ct. 2014), leading the Federal Circuit to vacate a District Court’s claim constructions and holdings on invalidity in Nevro Corp. v. Boston Scientific Corp. (Fed. Cir. April 9, 2020) (opinion by Judge Moore, joined by Judges Taranto and Chen). The lawsuit includes eighteen claims of seven related patents “directed to high-frequency spinal cord  stimulation  therapy  for  inhibiting  an  individual’s pain.” (Claims of U.S. Patent  Nos.  8,712,533; 9,327,125; 9,333,357; and 9,480,842 were at issue in the present decision; the other patents-in-suit are U.S.  Patent  Nos.  8,359,102; 8,768,472; and 8,792,988.)

The four claim terms at issue can (and should for present pedagogical purposes) be considered out of context, because just based on plain and ordinary meaning one can see that the terms provide functional description:

    • “paresthesia-free” (“paresthesia” undisputedly means “means “a sensation usually described as tingling, pins and needles, and numbness”);
    • “configured to”;
    • “means for generating”; and
    • “therapy signal.”

The Federal Circuit of course addressed each of these terms seriatim, but the interesting common thread is that the court not only found that the functional terms were not indefinite, but reaffirmed that Nautilus permits some ambiguity, i.e., more than one possible interpretation, without a finding of indefiniteness.

Indeed, as the court put it with respect to “paresthesia-free,” while this “is a functional term, defined by what it does rather than what it is,” this “does not inherently render it indefinite.” The district court had held the term indefinite because, even if it was clear what it meant to be free of the sensation of paresthesia, the district court thought it unclear how one skilled in the art would know in applying a signal if that effect was achieved for a patient. The Federal Circuit disagreed, explaining that one skilled in the art would know after the signal was applied if it had been effective; it was not required that one would know this before applying the signal.

Of even more interest was the court’s discussion of “configured to,” a functional transition phrase found in many software and electronics patent claims. The district court found the term indefinite after concluding it could reasonably construed “to mean one of two things,” either that a signal generator had the capacity to generate recited electrical signals with or without further programming, or that a signal generator “has been programmed . . . to generate the described electrical signals.” But the district court had applied the wrong test:

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.” [Citing Nautilus.] The test is not merely whether a claim is susceptible to differing interpretations. Such a test would render nearly every claim term indefinite so long as a party could manufacture a plausible construction.

Here, the specification, as well as the file history of one of the patents, made clear that it was contemplated that the signal generator would be programmed to generate signals. Thus, “‘a signal generator configured to generate’ means ‘a signal generator programmed to generate.’”

The recitation of “means for generating” of course was construed pursuant to 35 U.S.C. § 112 ¶ 6, requiring reference to a structure disclosed in the patent specifications. The district court had “held that the patents’ disclosures of a ‘generic signal generator’ as the corresponding structure’ was ‘not sufficient’ because signal generators were ‘already known in the prior art.’” But this was not the proper analysis. The Federal Circuit agreed that the inquiry was ended by the fact that “the asserted patent specifications’ “disclosed “a signal generator as the structure for this limitation.”

Finally, the court addressed the term “therapy signal.” The Federal Circuit agreed that the district court had properly held this term not indefinite. However, the district court erred in construing “therapy signal” as an “electrical impulse” or “electrical signal.” Why? Because the district court ignored the functionality inhering in the term: “[t]he plain language of the claims makes clear that the claimed ‘therapy signal’ is for pain-relief spinal cord stimulation therapy.” Both claims using the term, and the patent specifications, described the purpose and effect of the therapy signal as to reduce pain. Therefore, “a “therapy signal’ is ‘a spinal cord stimulation or modulation signal to treat pain.’”