Before Prost, Stoll, and Reyna. Appeal from the United States District Court for the District of Massachusetts.
Summary: A patentee that successfully petitioned to correct a patent’s inventorship by removing a named inventor was permitted to seek a second correction to restore the same inventor, based on an intervening claim construction that the patentee had opposed.
Egenera sued Cisco Systems for patent infringement. In response, Cisco petitioned for inter partes review (IPR) of Egenera’s patent. Seeking an earlier invention date for the patent so it could swear behind prior art in the IPR, Egenera successfully petitioned to remove one of the named inventors from the patent. The Patent Trial and Appeal Board declined to institute the IPR for reasons unrelated to the inventorship change.
After the inventor was removed, the district court construed the claim language “logic to modify” as a means-plus-function limitation, over Egenera’s opposition. The court found that the structure in the specification corresponding to this claim language was what the parties called the “tripartite structure.”
Following claim construction, Cisco argued that the removed inventor had invented the tripartite structure, and because he was no longer listed as an inventor, the patent was invalid for incorrect inventorship. Egenera responded that the patent’s inventorship should simply be corrected under 35 U.S.C. § 256 to restore the removed inventor. The district court found that Egenera was judicially estopped from restoring the removed inventor, and thus held the patent invalid. Egenera appealed, challenging the claim construction and the invalidity ruling.
Reviewing the claim construction, the Federal Circuit explained that claim terms lacking the word “means” are presumed not to be means-plus-function terms. However, this presumption is rebutted if a claim term recites “function without reciting sufficient structure for performing that function.” Egenera argued that the claim at issue recited structure in the form of “software, firmware, circuitry, or a combination thereof.” However, the Federal Circuit clarified that “the question is not whether a claim term recites any structure but whether it recites sufficient structure” for performing the recited function. In Egenera’s claim, the alleged structure was not sufficient to perform the functions attributed to the “logic to modify.” Thus, the Federal Circuit affirmed the district court’s means-plus-function construction.
Turning to invalidity, the Federal Circuit stated that judicial estoppel exists to prevent a litigant from taking a litigation position inconsistent with one successfully asserted in an earlier court proceeding. Egenera did not advance any “clearly inconsistent” positions because its petition to remove the inventor was consistent with the claim construction it was asserting at the time of the petition. Further, no other factors weighed in favor of judicial estoppel. Thus, the Court vacated the district court’s invalidity judgment and remanded for further proceedings.