Egenera, Inc. v. Cisco Systems, Inc., 972 F.3d 1367

Background

Egenera sued Cisco for infringement of U.S. Patent No. 7,231,430, which claims a software‑configured platform that creates virtual processing area networks.
After Cisco filed an IPR petition, Egenera petitioned the PTO to remove listed inventor Peter Schulter (a petition granted ministerially while the IPR was pending).
The district court construed several claim terms—including “logic to modify” —as means‑plus‑function under 35 U.S.C. § 112(f), identifying a “tripartite structure” (virtual LAN server, virtual LAN proxy, physical LAN driver) as corresponding structure.
Cisco litigated inventorship under pre‑AIA § 102(f), arguing Schulter conceived the tripartite structure; a three‑day bench trial found Schulter an inventor.
The district court held Egenera judicially estopped from relisting Schulter and therefore invalidated the patent for incorrect inventorship.
On appeal the Federal Circuit affirmed claim construction (means‑plus‑function and the tripartite structure) but vacated the invalidity judgment, holding judicial estoppel did not bar correction and remanding for further proceedings.

Issues

Issue	Plaintiff's Argument (Egenera)	Defendant's Argument (Cisco)	Held
Whether “logic to modify” is a means‑plus‑function term under §112(f)	“Logic” is a common technical term connoting software/firmware/circuitry and therefore sufficiently structural	“Logic” is a generic black‑box term lacking sufficient structure and thus invokes §112(f)	Affirmed: term invokes §112(f); Egenera failed to show sufficient structure
What specification structure corresponds to the claimed function(s)	The corresponding structure should be the broader control node or, if narrowed, primarily the virtual LAN proxy	The tripartite structure (virtual LAN server, proxy, physical LAN driver) functions in concert to perform the claimed modification	Affirmed: tripartite structure is the corresponding structure
Whether Schulter’s omission can be corrected under 35 U.S.C. §256 (meaning of “error”)	§256 allows correction; “error” includes deliberate as well as honest mistakes (supports relisting)	Characterized Egenera’s PTO petition as tactical/deceptive and thus not an “error” warranting correction	Held: “error” includes deliberate omissions; Schulter’s omission qualified as an “error,” so §256 could apply
Whether judicial estoppel bars Egenera from seeking correction after its PTO petition	Judicial estoppel cannot apply because the PTO §256 petition was a ministerial, non‑adjudicative filing and positions were not clearly inconsistent or persuasive to a tribunal	Egenera’s earlier PTO petition and signatures persuaded the PTO and gave Egenera an unfair tactical advantage, so estoppel should apply	Reversed: district court abused discretion; judicial estoppel did not apply (positions not clearly inconsistent; PTO ministerial action not sufficient acceptance; no unfair prejudice shown)

Key Cases Cited

Williamson v. Citrix Online, LLC, 792 F.3d 1339 (Fed. Cir. 2015) (rebuttable presumption against §112(f); standard for when a term lacks sufficient structure)
Phillips v. AWH Corp., 415 F.3d 1303 (Fed. Cir. 2005) (claim‑construction framework focusing on intrinsic evidence)
TEK Glob., S.R.L. v. Sealant Sys. Int’l, Inc., 920 F.3d 777 (Fed. Cir. 2019) (assessing sufficiency of structural disclosure for §112(f) analysis)
Stark v. Advanced Magnetics, Inc., 119 F.3d 1551 (Fed. Cir. 1997) (§256 “error” includes deliberate as well as honest mistakes)
New Hampshire v. Maine, 532 U.S. 742 (U.S. 2001) (three‑factor judicial‑estoppel test)
RFF Family P’ship v. Ross, 814 F.3d 520 (1st Cir. 2016) (First Circuit application of New Hampshire factors)
Pannu v. Iolab Corp., 155 F.3d 1344 (Fed. Cir. 1998) (patent invalidity may be avoided where inventorship can be corrected)
Trs. v. United States, 593 F.3d 1346 (Fed. Cir. 2010) (judicial estoppel can apply where an administrative tribunal is one of the prior forums)