35 USC §315(e)(2) prohibits a petitioner (or real party in interest or privy of the petitioner) in an Inter Partes Review (IPR) of a patent claim from asserting in district court litigation that "the claim is invalid on any ground that the petitioner raised or reasonably could have raised" during the IPR proceeding. This statutory IPR estoppel attaches as soon as the Patent Trials and Appeals Board ("PTAB") renders a final written decision in an IPR proceeding.
Although the PTAB has issued over 200 final written IPR decisions triggering estoppel in a parallel district court action since the introduction of the process in 2012, there is yet to be seen any real guidance from the district courts as to what constitutes a ground that "reasonably could have" been raised by a petitioner. Despite the lack of case law on what "reasonably could have" been raised means, we do have some guidance available to us outlining relevant exceptions to the could-have-raised estoppel.
The following grounds have been determined to be likely possibilities for a petitioner to raise in a subsequently filed district court proceeding if omitted from the IPR:
1. Patentable Subject Matter, Written Description, Enablement, and Indefiniteness Grounds
The could-have raised estoppel does not prevent a petitioner from asserting in a later filed district court action, that a claim is invalid for failing to comply with the patentable subject matter requirement, or any of the written description, enablement, and definiteness requirements of 35 USC §§ 101 or 112. Only challenges grounded in anticipation or obviousness based on prior art under 35 USC §§102 or 103 fall within the scope of the IPR estoppel provision. Under 35 USC §311(b), a petitioner can seek IPR review of patent claims "only on a ground that could be raised under section 102 or 103 and only on the basis of prior art consisting of patents or printed publications." Therefore, as none of these grounds could have properly been raised in an IPR proceeding, they can be later asserted by a petitioner in a district court proceeding without triggering the estoppel provision.
2. Reasonably Undiscovered Prior Art
Does a petitioner have to scour the earth to uncover every possible reference that could potentially be used to invalidate a patent in an IPR proceeding to avoid being estopped from later asserting it in litigation? The legislative history of the "could have raised" estoppel provision seems to indicate that the answer is no. It appears that the term "reasonably" restricts the scope of could-have-raised estoppel to that which "a skilled searcher conducting a diligent search reasonably could have been expected to discover." In other words, it is not necessary for a petitioner to conduct "a scorched-earth search around the world" in order to uncover all relevant prior art. While the legislative history suggests that this reasonably undiscovered prior art may avoid the scope of the IPR estoppel provision, the courts have not yet weighed in on what constitutes a reasonably diligent search and whether they will adopt the legislative history interpretation for "reasonably could have raised" for IPR estoppels.
Based on this exception to the estoppel provision, it would seem appropriate to conclude that a petitioner would be barred from asserting in a district court proceeding any grounds based on prior art which had been discovered but which had been intentionally or accidentally omitted from the IPR proceeding.
3. Prior Art Combinations and Use of Physical Products
The District Court for the Central District of California recently identified two exceptions to "could-have-raised" estoppel. In Star Envirotech v. Redline Detection, LLC et al., 8-12-cv-01861, 5 (C.D. Cal. January 29, 2015), and following a final written opinion by the PTAB finding the claims of the Star Envirotech patent to be patentable after challenged by Redline in an IPR proceeding, Redline subsequently cited seven references in a district in support of its position that the Star Envirotech patent was invalid. Star Envirotech argued that Redline references (six of which were used in the IPR proceeding while the seventh was a physical product made by Star Envirotech) should be stricken under the raised or could have raised estoppel provision, because Redline could have raised the product's owner manual as part of the IPR proceeding. The district court disagreed and found that the product could not have been raised in the IPR proceeding because it was not a patent or printed publication. The court held that the specific product referenced by Redline, alleged to disclose the features claimed in the Star Envirotech patent, included features that were not referred to in the owner's manual. Accordingly, this opinion supports the conclusion that a prior art device might not be barred by the estoppel provision of §315(e)(2), as long as at least one claimed feature is embodied in the physical machine and not in the published manual.
In addition, the court declined to estop the defendant from relying on the combination of the product with the six publications raised in the IPR proceeding, even though the references would be individually estopped under §315(e)(2).
This case seems to indicate that courts will not estop invalidity grounds based on a combination of references if even a single reference used in the combination is found to be outside the scope of §315(e)(2). Based on the exceptions to the "could have raised" estoppel provision, which have been slowly carved out for us thanks to case law and recent IPR decisions, IPR petitioners should err on the side of submitting all known references in an IPR proceeding, especially if the references (1) were known and not "undiscovered", (2) comprise patents or printed publications, and (3) support grounds for invalidity under §§102 or 103. Holding back such references would prevent the omitted references from later being submitted in a district court proceeding as a ground for invalidating a patent. Polsinelli attorneys are prepared to assist you in putting your best case forward in an IPR proceeding.
