Researching the Opposing Patent Expert

Most pre-retention due diligence goes into the expert a party is about to hire. The expert on the other side usually gets far less attention, even though the record is just as public and often just as decisive.

A recent Patent Trial and Appeal Board decision shows the payoff. In Interactive Communications v. Blackhawk Network (IPR2024-00465), the Board had found every challenged claim unpatentable. On Director Review, USPTO Director John Squires vacated that decision and terminated the proceeding, with no final written decision. The reason was the petitioner's expert. On cross-examination, the expert first testified that a key exhibit did not represent the modification described in his declaration, then reversed himself. Finnegan, summarizing the ruling, wrote that the Board "abused its discretion by crediting inconsistent and contradictory expert testimony." The patent owner kept its claims because it surfaced the contradiction in the opposing expert's testimony.

That work starts long before cross-examination. Most of the material an expert can be impeached with is already on the public record.

The opposing expert's record is public

Four sources carry most of it. PTAB final written decisions state, issue by issue, whether the Board credited an expert. District court Daubert orders state whether testimony was admitted, limited, or excluded. The expert's prior declarations state the positions they have taken under oath. Dockets and counsel-of-record fields show which parties and firms have retained the expert, and on which side.

None of it is hard to read. The work is aggregation: the same expert appears across dozens of proceedings, in different forums, under name variants, with the relevant facts spread across separate systems.

What to check

Credit-rate history. Every expert who has testified in an inter partes review has a credit-rate footprint, the share of credibility findings in final written decisions that come out in the expert's favor. The spread is wide. Among repeat experts, those with ten or more rulings, the top fifth are credited at least 80 percent of the time, while the bottom fifth are credited under 20 percent. When an opposing expert is in that bottom group, the Board has repeatedly declined to credit that expert, and that record is citable.

Daubert exposure. Two things matter here: whether a district court has excluded the expert, in full or in part, and how often opposing counsel has moved to exclude regardless of outcome. Repeated motion practice, even where the expert survived, signals a methodology that opposing counsel keeps challenging.

Prior inconsistent positions. An expert who took one position in a prior declaration and the opposite position in the current matter is exposed on cross-examination. As the Supreme Court has put it, "the testimony of one who has been found unreliable as to one issue may properly be accorded little weight as to the next." A credibility problem on one issue does not stay on that issue.

Conflicts and side history. An expert who previously worked for a party now on the other side can be disqualified. Finnegan recently set out the two-part test courts apply: whether it was objectively reasonable for the first party to believe a confidential relationship existed, and whether confidential information was disclosed to the expert. The inputs to that question, the expert's prior parties and firms, are in the representation record.

Rate and its consistency. Disclosed hourly rates build a public footprint. A rate that jumps between proceedings, or sits well above the comparable range, is cross-examination material on the opposing expert and a budgeting input on your own.

Why it is usually skipped

The information is public but scattered, and assembling it by hand for every opposing expert is slow. The American Bar Association's guide to selecting experts tells litigators to research candidates thoroughly and to use a commercial track-record database rather than rely on what an expert discloses. The same database works on the opposing expert.

How WitnessLens consolidates it

WitnessLens builds one profile per patent expert from the public record: PTAB credit history, Daubert outcomes, prior declarations, representation history by party, side, and firm, and disclosed hourly rates. Every field is filterable by court, year, technology area, and opposing counsel. Run it on the expert you are about to retain. Then run it on the opposing expert.

A note on the data

The credit-rate figures above (top fifth at 80 percent or more, bottom fifth under 20 percent) draw on PTAB final written decisions tracked on WitnessLens, where repeat experts are those with ten or more credibility evaluations. Methodology details are on the methodology page.