A Blog About Intellectual Property Litigation and the District of Delaware


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One of the more common issues to come up at trial is whether an to what degree an expert can exceed what is in their report. I've heard varying opinions on this from judges in Delaware and elsewhere. Some judges hold experts pretty tightly to their report; others apply something more akin to notice pleading, where the expert merely has to stay within the broad outline of what was addressed.

If you're going to have an expert on either side at trial, it's a good idea to know where your judge stands on this issue beforehand. We got a data point from Judge Andrews on this last week, when he issued a memorandum order on a motion to strike expert testimony for exceeding the report.

When the defendant objected at trial, Judge Andrews let the testimony in (pretty common in a bench trial), and addressed the issue on a later motion to strike.

The defendants argued that plaintiffs' expert offered a view on a term used in a patent specification, "preformulation," that he had never presented in his report:

Defendants contend that Dr. Berkland for the first time at trial "testified that the meaning of the term 'preformulation,' in the context of the patent specification, is 'a completely different definition' from how a POSA would understand it." . . . Defendants argue that Dr. Berkland's expert report only uses the term "preformulation" once, and it does not provide a definition for that term.

The Court agreed, and struck the testimony:

I agree with Defendants that Dr. Berkland's opinion regarding the meaning of the term "preformulation" was not previously disclosed in his expert report. His testimony regarding the meaning of the term should therefore be stricken. The single paragraph of Dr. Berkland's report that Plaintiffs cite . . . does not say anything about what a POSA would understand the terms "preformulation" or "preformulation composition" to mean, let alone that a POSA would understand the terms to deviate from their normal meanings.

Plaintiffs tried to argue that even if the definition was new, it was offered in response to a new argument from defendants' expert. The Court rejected that idea too.

Judge Andrews seemed to agree that could excuse new testimony generally. But when the Court compared the defendants' expert testimony to that experts' report, it found them to be consistent:

I disagree with Plaintiffs that Dr. Berkland's testimony is proper because it was in response to a new opinion from Dr. Gemeinhart. Dr. Gemeinhart's expert report recites, "The first step in dosage for[m] design is the completion [of] preformulation research where the stability and physico-chemical properties of the active pharmaceutical ingredient ('API') are measured." . . . Dr. Gemeinhart's testimony at trial . . . is entirely consistent with his expert report.

The Court therefore struck all of the expert's testimony regarding the meaning of that term. The Court, however, declined to strike every time he used the term "preformulation"—instead, it carefully addressed only the portions of the transcript where the expert testified as to its meaning:

I think Dr. Berkland's testimony at Tr. 378:9-16; 379:24-380:12, 382:4-25; 412:13-22; and 429:21-431 :12, does not need to be stricken. While Dr Berkland may use the word "preformulation" in this testimony, he is not testifying about the meaning of the term. Rather, he is testifying about what the relevant part of the patent specification says or what a POSA would understand the specification to be teaching. Just because he did not offer a definition of the word "preformulation" in his expert report does not prevent him from using the word.

Finally, Judge Andrews declined to strike other testimony, where he found the expert was "merely elaborating on his expert report."

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