PTAB Makes Broadest Interpretation on Estoppel in IPRs

November 12, 2018
Post by Oliver P. Couture, Ph.D.

Drafting post grant proceeding petitions needs to be done carefully due to their limited space. Last week, the Patent Trial and Appeal Board (PTAB) further increased the pressure to use the limited number of words effectively when Kingston Technology Company, Inc. v. Spex Technologies, Inc. (Case IPR2018-01002) was entered. Kingston, the petitioner, attempted to file a second IPR based on different grounds for the same claims as a first IPR before the final written decision. During the IPR, the PTAB ordered briefings on why Kingston should not be estopped from bringing the second IPR.

Kingston argued that estoppel did not apply because under PTAB rules, they could not bring the new grounds for the first time during the prior IPR because the IPR had already been instituted, citing Shaw for support. However, this did not persuade the PTAB. First, the PTAB held that Shaw was inapposite in this instance due to being prior to SAS, which changed how the PTAB handled multiple grounds in a single IPR. The PTAB held that post-SAS IPRs had every ground for every claim  either instituted or denied, whereas Shaw was a case dealing with only a particular ground being denied in a prior IPR.

Second, the PTAB was not convinced because finding in favor of Kingston would render the phrase “or reasonably could have raised” in 315(e) meaningless. The PTAB found that Kingston’s argument was that estoppel only applied to grounds raised in prior IPRs and not on any reasonable ground a petitioner could have raised. The PTAB found this interpretation of current PTO policy in direct conflict with the broad definition found in the legislative history of the AIA and the plain meaning of 315(e).

This IPR combined with SAS may make the 14,000 words of an IPR even more precious as now petitioners may not have enough room to put forth every ground possible. However, this may be exactly what the PTAB intends and it may be better to only go forward with your best argument.

Oliver P. Couture is an Intellectual Property Attorney in the Biotechnology & Chemical Patent Practice Group at McKee, Voorhees & Sease, PLC. For additional information please visit or contact Oliver directly via email at

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