Intellectual Property » A Limit on Expert Testimony in Patent Cases

A Limit on Expert Testimony in Patent Cases

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August 9, 2019

Expert witnesses in a patent case can testify to a lot of things, but according to attorney Daniel Hanson, obviousness is not one of them. It may be common practice, but in his opinion such testimony should be objected to and stricken as irrelevant, and a motion in limine ought to be used to prevent it from coming before a jury. Regardless of their mastery of their field, an expert’s expertise does not extend to questions of law and no witness, not even an expert, can render a legal opinion. He references the case of Millennium Pharm., Inc. v. Sandoz Inc., decided by the Federal Circuit in 2017, to demonstrate what happens when expert testimony strays into legal questions. The decision showed that the experts did not understand legal standards, because they concluded that the claimed invention could still be obvious in spite of fatal gaps in the prior art evidence. They’d testified that obviousness was present, when as a matter of law, it was not present; and the district court made a reversible error by adopting those experts’ conclusions. Expert opinion on obviousness should also be excluded from quasi-judicial proceedings before the USPTO, such as cases of inter partes review, he says. The agency’s rules of evidence are not identical to the federal courts, but they still should be bound some rules. Expert testimony on obviousness is irrelevant, and irrelevant subject matter must be excluded.

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