As accused infringers rush to challenge patents in trials before the Patent Trial and Appeal Board, they must consider the estoppels of 35 U.S.C. § 315(e). The estoppel statute may prevent petitioners from later raising any ground of unpatentability that was raised, or could have been raised, during the PTAB trial. If claims survive, the accused infringer may be left without prior art patents or printed publications to present in district court, and should consider other types of prior art: prior art use or sale in the United States.

As district courts consider challenges based on these estoppel provisions, accused infringers may draw insight from the outcomes. In the context of district court, 35 U.S.C. § 315(e)(2) states that:

The petitioner in an inter partes review of a claim in a patent under this chapter that results in a final written decision under section 318(a), or the real party in interest or privy of the petitioner, may not assert either in a civil action arising in whole or in part under section 1338 of title 28 or in a proceeding before the International Trade Commission under section 337 of the Tariff Act of 1930 that the claim is invalid on any ground that the petitioner raised or reasonably could have raised during that inter partes review.

In a recent decision, Star Envirotech, Inc. v. Redline Detection, LLC, Case No. 8:12-cv-01861, slip op. (C.D. Cal. Jan. 29, 2015), the District Court denied the plaintiff patent owner’s motion to strike the defendants’ preliminary invalidity contentions that relied on a LeakMaster A240 smoke machine, made and sold within the United States prior to the effective filing date of the patent-in-suit, U.S. Patent No. 6,526,808. The defendants presented the manufacture and sale of the smoke machine as prior art, in combination with each of six prior art documents.

The plaintiff’s motion was based on the defendants’ previously filed petition for inter partesreview of the patent-in-suit (Case No. IPR2013-00106), which ended in a final written decision finding that the two challenged claims had not been shown to be unpatentable. The patent owner moved to strike the preliminary invalidity contentions, arguing that while the LeakMaster itself was not available for submission in the IPR, which is limited to patents and printed publications, the defendants could have submitted the LeakMaster’s instruction manual. According to the plaintiff, the defendants were aware of the instruction manual at the time of the IPR petition, and therefore could have raised a ground of invalidity based on the owner’s manual. Since the defendants invalidity contentions were based on the prior art use of the LeakMaster, the plaintiff argued that the use described by the instruction manual is indistinguishable from the use described by the physical machine.

The District Court, however, found that the LeakMaster, as a machine, was a “superior and separate reference” from the instruction manual, disclosing claimed features that were not included in the instruction manual. According to the Court, the LeakMaster could be dissembled to address claim limitations that the manual did not address. The Court therefore denied the motion.

The Court noted that the plaintiff did not challenge the availability of the other six prior art documents when used in combination with the LeakMaster, though the documents themselves were raised, and could have been raised, in the IPR. The decision therefore turned solely on the availability of the LeakMaster.

Thus, when considering the estoppels of 35 U.S.C. § 315(e)(2), accused infringers should take note of real-world products, or other non-publication prior art, that may be related to prior art presented in the Patent Office.