Expert Testimony Must Be Supported by Evidence

by McDermott Will & Emery

Corning Inc. v. DSMIP Assets B.V.

The Patent Trial and Appeal Board (PTAB) issued final written decisions in 10 inter partes review (IPR) challenges.  Although early IPR decisions generally have sustained petitioners’ challenges, here the PTAB largely sided with the patent owner, upholding 157 out of 209 challenged claims spanning across eight related patents.  Corning Inc. v. DSM IP Assets B.V., Case Nos. IPR2013-0043 and IPR2013-0044 (PTAB, May 1, 2014) (McKelvey, APJ); IPR2013-0045 (PTAB, May 9, 2014) (Obermann, APJ); IPR2013-0046 (PTAB, May 1, 2014) (Bisk, APJ); IPR2013-0047 (PTAB, May 1, 2014) (McKelvey, APJ); IPR2013-0048 (PTAB, May 9, 2014) (Kamholz, APJ); IPR2013-0049 (PTAB, May 9, 2014) (Kamholz, APJ); IPR2013-0050 (PTAB, May 1, 2014) (Kamholz, APJ); IPR2013-0052 (PTAB, May 1, 2014) (Yang, APJ); IPR2013-0053 (PTAB, May 1, 2014) (Yang, APJ).

The patents at issue generally relate to coated optical fibers that are commonly used in fiber-optic communications and data transmission.  Corning filed IPR petitions challenging the eight patents held by DSM IP Assets, even though DSM had never asserted its patents against the petitioner.

Expert Opinion

In the final decisions, the PTAB took particular notice of the expert reports and testimony that were used by the opposing parties to develop their arguments.  The PTAB was skeptical of statements made by experts if such statements were found to be unsupported by underlying data.  This was especially true where experts “repeated, verbatim, attorney argument from the parties’ submissions” that did not identify objective supporting evidence.

The PTAB noted that expert assertions must be substantiated by evidence, explaining that even if it had no specific reason to question the soundness of an expert’s assertion, without citation of supporting evidence for an assertion, the PTAB can assign little or no weight to the expert’s opinions and testimony.  As the PTAB explained, “an expert’s opinion is only as good as the facts on which it is based.” 

The PTAB further explained that it will give consideration only to the arguments made by the parties and the evidence cited in support of those arguments.  The PTAB “will not scour the record in search of evidence relevant to a particular issue, nor will it attempt to fit evidence together into a coherent explanation that supports an argument.”

Scope of Opposition

The PTAB also explained its rule that a reply may only respond to arguments raised in the corresponding opposition.  Where a reply raises a new issue or belatedly presents evidence, that new evidence or issue will not be considered.  In one IPR, Corning attempted to submit evidence, based on post-petition experimentation and the testimony of three previously undisclosed witnesses, that purported to show that the prior art met the claim limitations being reviewed.  The PTAB determined that consideration of the new evidence would be unfairly prejudicial to DSM because DSM would not have the opportunity for rebuttal.  The PTAB did indicate that Corning’s evidence might have been permitted had DSM been given the opportunity to rebut the new theory.

Practice Note: An explanation of the experimental methods used to generate results is an essential part of experiment-based expert testimony.  An expert must explain not only what their conclusions are, but how and why they arrived at them.


DISCLAIMER: Because of the generality of this update, the information provided herein may not be applicable in all situations and should not be acted upon without specific legal advice based on particular situations.

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