Intellectual Property > IP Newsflash > Estoppel Applies to “Known or Used” Prior Art if PTAB Considered Corresponding Written References
04 Jan '19

A district court in California has granted-in-part a Plaintiff’s motion for summary judgment of no invalidity under 35 U.S.C. § 103 due to inter partes review (IPR) estoppel. During the pendency of the litigation, Defendants filed 10 IPR petitions. The Patent Trial and Appeal Board (PTAB) issued final written decisions finding that four patent claims asserted in the litigation were not unpatentable.

In response to the PTAB decisions, the Plaintiff in the district court moved for partial summary judgment of no invalidity of the same four claims due to IPR estoppel pursuant to 

35 U.S.C. § 315(e)(2). As the district court explained, the grounds that a petitioner reasonably could have raised in an IPR (which trigger estoppel) include prior art that a skilled researcher conducting a diligent search reasonably could have been expected to discover.

With respect to the four obviousness challenges that Plaintiff addressed in its motion for summary judgment, Defendants did not dispute that they were aware of the relevant art at the time that they filed the IPR petitions. Instead, Defendants argued that they could not have raised their district court invalidity challenges in the PTAB because they relied on the art in the district court not as “patents or printed publications” under pre-AIA
Section 102(b), but as information that was “known or used by others” before the patented inventions under pre-AIA Section 102(a)—an argument that they could not have raised at the PTAB because the PTAB’s consideration of prior art is limited to patents and printed publications. In response, Plaintiff argued, inter alia, that, where alleged prior art is a written document, the standard for establishing the reference as a “printed publication” is substantively the same as the “known or used” standard, and the relevant material must still be “publicly accessible.” Thus, according to Plaintiff, Defendants were making the same argument that they lost before the PTAB and should be estopped.

For three of the alleged invalidity challenges, the court agreed. The court found that Defendants sought to use the relevant references themselves as the basis for their invalidity arguments (as opposed to corroborative evidence). One invalidity challenge, however, included additional evidence—emails between two authors of relevant references relating to the ideas expressed in their work, and related testimony. The court noted that it was not clear whether the emails and testimony were intended to establish a reason to combine two references, as opposed to showing that certain elements of the invention were “known or used by others.” Nevertheless, and despite the court’s skepticism about the “public accessibility” issues surrounding the information in the emails and testimony, the court noted that the issue had not been squarely addressed by Plaintiff and declined to extend IPR estoppel to that challenge at the summary judgment stage. Accordingly, the district court granted Plaintiff’s motion for summary judgment of no invalidity based on IPR estoppel, except as to Defendants’ invalidity challenge that relied on the combination of prior art, testimony and email evidence.

Practice Tip: If one asserts substantively the same reference in the PTAB and a district court on a theory that the written reference is separate evidence of what was known or used by others before the invention, IPR estoppel may attach based on a final written decision by the PTAB. IPR estoppel may not attach, however, if additional evidence, beyond the reference itself, which could not be raised in an IPR, is introduced at the district court.

Cal. Inst. Of Tech. v. Broadcom Ltd., et al., CV 16-3714 (C.D. Cal. Dec. 28, 2018) (Dkt. No. 830)