Addressing the proper construction of a means-plus-function limitation, the U.S. Court of Appeals for the Federal Circuit held that courts cannot use structures from prior art references listed in the patent-in-suit to provide corresponding structure for a means-plus-function limitation. Pressure Products Medical Supplies, Inc. v. Greatbatch Ltd., Case No. 08-1602 (Fed. Cir., Mar. 24, 2010) (Rader, J.) (Newman, J., dissenting in part).

Pressure Products sued Greatbatch (d.b.a. Enpath Medical) for infringing a patent directed to a medical device known as an introducer, which “permits a surgeon to place and remove catheters or pacemaker leads into blood vessels during surgical procedures.” In order to remove an introducer from a patient’s body, a surgeon must split the introducer’s sheath. Pressure Products’ claimed invention included a “means for permitting removal of [the introducer sheath].”

The magistrate judge ruled that “means for permitting removal” required construction as a means-plus-function limitation. The magistrate judge determined that the corresponding structure for the claimed function was “score lines,” which the magistrate judge defined as “one or more line(s) defined in the hemostatic valve and introducer sheath.”

In the middle of trial, the district court, sua sponte, supplemented the definition of “score lines” to include structures disclosed in “a laundry list of prior art references” listed in the patent-in-suit. Applying the new claim construction, the jury returned a verdict of infringement. Enpath appealed.

On appeal, an expanded (five-judge) panel of the Federal Circuit held that supplementing the definition of a claim term during trial was not objectionable. The Court cited its own precedent that “district courts may engage in a rolling claim construction, in which the court revisits and alters its interpretation of the claim terms as its understanding of the technology evolves.” Nevertheless, four of the five judges vacated the district court’s claim construction, holding that the district court “erroneously used structures from the prior art references listed in the patent to provide a definition for score lines encompassing structures not disclosed expressly in the patent specification.” The four-judge majority reasoned that prior art references, identified in a patent by their titles and citations, do not provide a description sufficient to give the patentee the right to claim the structures disclosed in the prior art.

Judge Newman dissented, finding that the structures disclosed in the cited prior art references were “incorporated by reference in the specification” of the patent-in-suit. Judge Newman rejected the majority’s reliance on Atmel Corp. v. Information Storage Devices, reasoning that Atmel did not create a blanket rule prohibiting a patentee from relying on an incorporated reference to describe a corresponding structure. Rather, Judge Newman distinguished Atmel on the grounds that it involved a situation in which the only structure described to perform the claimed function came from the incorporated reference. In Pressure Products, she noted the incorporated references did not provide the only disclosure of corresponding structure.