Although it is unclear whether PTAB decisions are given collateral estoppel effect in district court proceedings, PTAB decisions are at least persuasive authority. And as one court observed, “ignoring the PTAB decision entirely smacks of folly.” Yet, a third time was not the charm when a defendant argued the same position to the court three times, the third coming after a contradictory PTAB ruling.

The case of Microwave Vision, SA et al v. ESCO Technologies, Inc. et al., 1-14-cv-01153 (GAND September 20, 2016) involves claims directed to over-the-air measurement devices, including multi-probe systems. The relevant claims were written in means-plus-function format, requiring corresponding structure to be disclosed in the specification or else the claims would be found indefinite. At issue was whether the “network of probes” and “support” in the claims are both required to pivot, or if only one of the elements is pivotable. Defendant argued the claims are broad enough to cover both elements pivoting, for which there was no corresponding structure in the specification, and therefore argued the claims were indefinite. Plaintiff disagreed and argued such a construction would not be supported by the specification in any event, as there is no embodiment where both elements pivot. The district court found corresponding structure during Markman, and again during a Motion to Reconsider the Markman order.

The defendant then filed a Petition for Inter Partes Review before the PTAB. The Petition was denied, but in the process, the PTAB found the Petition failed to submit prior art that disclosed both of the elements were pivotable. In doing so, the defendant argued the PTAB implicitly found the claims were broad enough to require both of the elements to be pivotable, rather than only one of the elements. Because there was no corresponding structure for both elements being pivotable, the defendant argued the claims were indefinite.

The court, for the third time, again found the claims included sufficient structure and discounted the implicit findings of the PTAB as not bearing on the issue of indefiniteness:

[T]he PTAB . . . found that the [patent’s] Specification itself failed to ‘clearly associate the combination of separate structures disclosed in Figures 1 and 2 as corresponding to the claimed dual functions.’… [T]he PTAB expressly disclaimed any indefiniteness analysis. …At bottom, and regardless of whether the analysis is framed in patentability or indefiniteness terms, the PTAB and this Court simply disagree that the [patent] fails to ‘clearly associate’ the structures in Figures 1 and 2 with the ‘both’ pivot function. 


PTAB decisions are given great weight in corresponding district court cases. The PTAB is seen as a body of patent experts that district court judges are reluctant to disagree with. Here, the PTAB’s finding was weakly associated with indefiniteness, and the court had already conducted an extensive analysis into this issue two times prior. Still, prior PTAB decisions should not be overlooked in district court proceedings, as even this court made clear.