Acco Brands, Inc. v. PC Guardian Anti-Theft Products, Inc., 3-04-cv-03526 (N.D.Cal., December 4, 2008).
Infringers have long been reticent about filing for inter partes reexamination. One problem is the estoppel provision – 35 U.S.C. § 315(c) – that limits the claims that the third-party requester can later make in court. In particular, Section 315(c) is written to estop the third party requester from later asserting an invalidity defense in litigation if the third-party requester "raised or could have raised" the ground during the reexamination. (The estoppel provision only applies once the PTO determines that the challenged claim is valid).
35 U.S.C. §315(c): A third-party [inter partes] requester … is estopped from asserting at a later time, in any civil action … the invalidity of any claim finally determined to be valid and patentable on any ground which the third-party requester raised or could have raised during the inter partes reexamination proceedings.
In this case, the PC Guardian had requested an inter partes reexamination based on several prior art references. However, upon consideration, the PTO confirmed that the claims were patentable.
In the ensuing infringement litigation, PC Guardian made an end-run around the estoppel argument. For its non-infringement contention, PC Guardian presented three 1980's Macintosh portable computers as prior art. According to the defendant's argument, the physical computers when seen in combination with the references considered by the PTO rendered ACCO's patent obvious.
Because reexaminations are restricted to considering only patents and printed publications, the district court agreed that Section 315 does not estop PC Guardian from asserting the combinations during litigation.