What Makes An Expert: Limits On Patent Expert Discovery

• Published date: 13 October 2022
• Subject Matter: Intellectual Property, Litigation, Mediation & Arbitration, Patent, Trials & Appeals & Compensation
• Law Firm: Baker Botts
• Author: Mr Nick Palmieri

The use of expert testimony can be critical in supporting or defending a patent infringement lawsuit. Given the complex technical nature of many patent disputes, an expert witness is typically needed to explain the how the patented features and prior art would be understood by a person of ordinary skill in the art, the function and properties of accused techniques, and even the vocabulary used therein.

But the scope of an expert's testimony is not unlimited. The Federal Rules of Evidence set forth the requirements for any testimony that is proffered by an expert.¹ These requirements are the enforced by the trial judge who is empowered with a "gatekeeping function" that "imposes a special obligation upon a trial judge to 'ensure that any and all scientific testimony . . . is not only relevant, but reliable.'" Carlson v. Bioremedi Therapeutic Systems, Inc., 822 F.3d 194, 199 (5th Cir. 2016) (citing Kumho Tore Co. v. Carmichael, 526 U.S. 137, 147 (1999)). The Supreme Court identified this gatekeeping function in Daubert v. Merrell Down Pharmaceuticals, Inc., 509 U.S. 579 (1993), noting that the Federal Rules of Evidence do not prevent the trial judge from "screening" proffered evidence for reliability based upon established scientific and legal principles.

This article addresses certain common grounds upon which parties to a patent infringement action may challenge the reliability of an opposing party's witness. While myriad potential grounds of objection exist, the article will focus on three:

• Failure to properly oversee testing of accused products;
• Improper bias or oversight introduced by the presenting party and
• Reliance upon concurrent litigation as evidence of a lack of non-infringing alternatives.

Improper oversight of product testing

One goal of Daubert is to ensure the reliability of evidence presented by an expert. It follows logically that where an expert has not overseen or in any way supervised testing of accused (or other) products in a patent infringement case, the Court may properly exclude such evidence.

A purpose of introducing expert testimony during trial is to present technical or other specialized evidence for the jury, or finder of fact, to understand the underlying technology. Yet under Duabert, experts must present a basis for their opinions beyond shallow conclusions drawn from test results or other evidence over which the expert provided no oversight. Where the expert has not guided testing or examination of the products at issue...