Find Contradictions in Expert Witness Testimony Using AI

TL;DR: The most useful material against an expert is what they said before about the same standard, on similar facts, as the opinion they're giving now. Finding it takes five steps: break the current opinion into claims, collect the prior record, filter it to this case, compare claim by claim, and turn the findings into a Rule 702 motion and a cross-examination outline. A team can run these steps by hand, or a purpose-built AI such as newcase.ai can run all five automatically, with a page-line citation and the expert's exact words on every finding.

Key Takeaways

• FRCP 26 requires experts to list every case they testified in over the past 4 years and every publication from the past 10. The list names the cases. The transcripts still have to be collected.

• Since December 2023, the party offering an expert must show the court it's "more likely than not" that the opinion meets Rule 702.

• The most valuable contradiction concerns the key question in your case.

• Every finding needs a page-line citation and the expert's exact words.

• newcase.ai Expert Witness Investigation runs all five steps automatically: it collects the prior record, filters it to your case, compares it with the current report and flags contradictions with citations.

Physicians and other medical experts make up about 40% of testifying experts in federal civil trials. Many of them have testified dozens of times, and only a small share of that testimony touches the question in your case. Start from the current opinion and pull only the prior record that tests it. That keeps the work focused on passages you can use.

Why should expert research start from the current case?

Relevance makes prior testimony usable. A prior statement supports impeachment or a Rule 702 motion when it contradicts the opinion the expert is giving now, on the same question and similar facts. Starting from the current opinion keeps the research narrow and makes every finding usable in a motion or a cross-examination.

The rules support this. Under the 2023 amendment to Rule 702, the party offering the expert must show that the expert's opinion "reflects a reliable application" of their methods "to the facts of the case." The Advisory Committee called treating these questions as matters of weight "an incorrect application" of the rule. An expert who applied a different standard to similar facts last year has a reliability problem this year.

The 5-step method for finding contradictions in expert testimony

Hypothetical used throughout

A patient comes to the emergency department with fever and confusion. Antibiotics are started 2 hours and 40 minutes after triage. The patient develops septic shock. The expert's report says the standard of care required antibiotics within 1 hour.

The Surviving Sepsis Campaign guidelines draw a line that matters here. They call for antibiotics within 1 hour for septic shock or probable sepsis, and within 3 hours for possible sepsis without shock. The 2026 update kept both timelines and rated the evidence behind them "very low certainty." So the opinion depends on one question: how did this patient look at triage?

Step 1: Break the current opinion into testable claims

Break the report into separate claims. Here there are three:

• The standard required antibiotics within 1 hour.

• The patient met criteria for probable sepsis at triage.

• The delay caused the shock.

Each claim becomes a search target.

Manually: an attorney reads the report and writes out the claims. With newcase.ai: the platform pulls the opinions, the methods and the facts relied on directly from the report.

Step 2: Collect the full prior record

Start with the expert's disclosure. FRCP 26(a)(2)(B) requires a list of all publications from the previous 10 years, every case in which the expert testified at trial or by deposition in the previous 4 years, and their compensation.

That list names the cases. Transcripts, reports, published articles and prior court rulings on this expert still have to be gathered.

Manually: a paralegal requests transcripts from counsel in each listed case, court reporters and deposition banks, then pulls the publications. With newcase.ai: the expert's prior testimony and publications are collected and indexed in one place, so they can be searched by issue.

Step 3: Filter to what bears on this case

Search the prior record for each claim from Step 1. For the hypothetical, that means:

• Any testimony on antibiotic timing.

• Any testimony on the difference between possible and probable sepsis.

• Any testimony on whether earlier antibiotics would have changed the outcome.

The facts of the current case decide what counts. If the triage record shows a normal blood pressure and an unclear source of infection, the expert's earlier statements about the 3-hour window become the most important material in the file. A newcase.ai medical chronology gives you that triage timeline, with vitals, labs and timestamps cited to the page of the chart.

Manually: keyword searches across every transcript, then reading every hit. With newcase.ai: the prior record is searched by meaning against each claim and against the medical chronology, so "three hours is acceptable" and "I wouldn't fault a clinician for waiting" both surface.

Step 4: Compare claim by claim

Put each current claim next to the relevant prior statement.

Every row needs an exact citation and the expert's exact words. When the expert answers, "That's not what I said," the verbatim quote settles it.

Manually: an attorney builds this table by hand from the filtered passages. With newcase.ai: the comparison is generated automatically, with each prior statement quoted verbatim and cited by page and line.

Step 5: Turn findings into a Rule 702 motion and a cross-examination outline

Sort each finding by what you'll use it for:

• Contradictions on the same standard go into the Rule 702 argument that the method was unreliably applied to these facts.

• Prior inconsistent statements go into the cross-examination outline. Under FRE 613(b), the witness must get a chance to explain or deny the statement before extrinsic evidence of it comes in.

• The expert's own publications can be read to the jury under the learned treatise rule, FRE 803(18), once they're established as reliable authority.

Manually: an attorney drafts the motion sections and the cross outline. With newcase.ai: Deposition Prep turns the cited findings into question sequences for the expert's deposition.

"An expert may have years of public testimony and publications. The challenge is identifying what actually matters to the opinion they are giving in your case."

Nader Karayanni, CEO and Co-Founder, newcase.ai

How long does expert witness research take?

It scales with the expert's testimony history. Take an expert with 30 prior depositions of about 200 pages each. That's roughly 6,000 transcript pages. At the paralegal benchmark of 20 to 25 pages an hour, reading them once takes 240 to 300 hours, before any comparison work starts.

Can AI find inconsistencies in an expert's prior testimony?

Yes, when it searches by meaning and cites every match. Experts rarely repeat their exact words across cases, so keyword search misses most contradictions. Legal-specific AI matches statements by meaning across hundreds of transcripts. Each match should point to the page and line and quote the testimony verbatim, so an attorney can check it in seconds.

FAQ

How do I find an expert witness's prior testimony?
Start with the FRCP 26 disclosure, which lists every case the expert testified in over the past four years. Then get the transcripts through counsel in those cases, court reporters, deposition banks and court dockets. Add the expert's publications and any rulings on challenges to their testimony. newcase.ai collects and indexes this record automatically.

What must an expert disclose about prior testimony?
Under FRCP 26(a)(2)(B), a retained expert's report must include their opinions and the basis for them, the facts considered, their qualifications with all publications from the previous 10 years, a list of cases where they testified in the previous 4 years, and their compensation. Many state rules require similar disclosures.

Can you impeach an expert with their own published articles?
Yes. A statement in the expert's own publication that contradicts their testimony can be used as a prior inconsistent statement under FRE 613. If the publication is established as a reliable authority, passages can also be read into evidence under the learned treatise exception, FRE 803(18). Quote the passage exactly and cite the publication.

What changed in Rule 702 in 2023?
The December 1, 2023 amendment made clear that the party offering the expert must show, more likely than not, that the testimony meets every Rule 702 requirement, including reliable application of the method to the facts of the case. The Advisory Committee called treating these questions as matters of weight an incorrect application of the rule.

Can AI automate expert witness research?
Yes. A purpose-built platform such as newcase.ai runs the full workflow: it pulls the claims from the current report, collects the expert's prior record, searches it by meaning against your case, and flags contradictions with verbatim quotes and page-line citations. The attorney reviews the findings and decides how to use them.

The Bottom Line

Start from the opinion in front of you. Filter the expert's history to what bears on it. Cite every finding by page, line and exact words. You can run the five steps by hand, or let newcase.ai run them automatically so your team starts from the contradictions.

See how newcase.ai Expert Witness Investigation runs all five steps automatically on the expert in your case.

Sources

• Federal Rule of Evidence 702, Cornell LII

• Federal Rule of Civil Procedure 26, Cornell LII

• Federal Rule of Evidence 613, Cornell LII

• Federal Rule of Evidence 803, Cornell LII

• Reference Guide on Medical Testimony, Federal Judicial Center

• Surviving Sepsis Campaign Guidelines 2021, SCCM

• Surviving Sepsis Campaign Guidelines 2026, Intensive Care Medicine

• 3 Methods for Preparing a Deposition Summary, Paralegal Bootcamp