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See the 60-second demo →The 2023 amendment to Federal Rule of Evidence 702 sharpened the Daubert gatekeeping function: courts must now affirmatively find that expert testimony is more likely than not the product of reliable principles applied reliably to the facts. That shift gives plaintiff attorneys more leverage to exclude weak defense experts — and more risk that their own experts get excluded.
This is the practical 8-factor checklist for evaluating whether a Daubert motion is worth filing, what to put in it, and what wins.
Daubert challenges methodology and qualifications, not factual disagreement. If the issue is "the witness reached the wrong conclusion," that's cross-examination at trial. If the issue is "the witness used a methodology that doesn't reliably produce conclusions," that's Daubert. Get this wrong and you waste judicial credibility. Get it right and you exclude a defense expert before the jury ever sees them.
The right test: ask "could a competent expert in this specialty apply this methodology and reach a different conclusion?" If yes, it's a credibility issue. If no — if the methodology itself is flawed — it's Daubert.
The strongest qualifications challenges target witnesses opining outside their narrow expertise — a general internist offering opinions on neurosurgical technique, an emergency physician opining on long-term oncologic outcomes. Cite Federal Rule of Evidence 702(a) and the witness's own CV.
Look for "litigation-only" methodologies — biomechanical reconstruction techniques used only by plaintiff or defense experts, differential diagnosis approaches that exclude likely causes without explanation, or causation frameworks that don't appear in the medical literature.
FRE 702(b) requires testimony to be "based on sufficient facts or data." Defense experts who base opinions on a 30-minute review of selected records — without examining the patient, without reviewing nurses' notes, without considering the full medication record — are vulnerable on this prong.
FRE 702(d) requires that the witness reliably apply principles and methods to the facts. Courts increasingly grant Daubert motions where the expert's analytical leap from "evidence X" to "conclusion Y" is unexplained or relies on intuition rather than methodology.
Prior contradictory testimony goes to credibility, not admissibility under Daubert directly — but a pattern of opportunistic position-taking can support an argument that the witness's methodology is "results-driven" rather than principled. (See FRE 702 Advisory Committee notes on the 2023 amendment.)
Many defense experts get current guideline citations wrong. Pull the actual document. Check edition dates. If the alleged negligence occurred in 2019 but the witness cites the 2024 guideline, that's an admissibility-level mistake.
Bias is generally a credibility issue, not Daubert — but extreme bias (e.g., 100% of testimony for one side, repeated work for the same defense firm) can support an argument that the methodology is results-driven.
The Supreme Court in General Electric Co. v. Joiner, 522 U.S. 136 (1997), held that courts may exclude opinions where there is "simply too great an analytical gap between the data and the opinion proffered." This is the "ipse dixit" doctrine — the expert's say-so isn't enough. If the witness can't articulate why X leads to Y, that's a Daubert ground.
Daubert motions are typically filed at one of two points:
Either timing works. The risk of filing too early: discovery isn't complete, and the witness may correct disclosure deficiencies before the hearing. The risk of filing too late: the court may treat the motion as a motion in limine on credibility rather than a true Daubert challenge.
Empirically, Daubert motions on medical experts succeed in roughly 25-40% of cases that reach a written ruling. But this number is misleading because of selection bias — most filed motions are filed against weak experts in the first place. The actual question for you, on your case, is: does this expert's methodology have a fatal flaw the court would need to address?
If you can articulate the flaw in 200 words and cite three peer-reviewed publications and the witness's own deposition admissions, you have a winnable motion. If you find yourself reaching for "the testimony is unhelpful to the jury" in the alternative, you don't.
Daubert motions are filed in maybe 10-15% of medical-malpractice cases. The other 85% involve expert testimony that's strong enough to survive Daubert but weak enough to be devastated at cross-examination. Treat your Daubert analysis as a triage step: Daubert-grade weakness → motion. Weaker-but-not-fatal flaws → cross-exam binder.
The cross-exam binder is where most cases are actually won. Use the same 8 factors, but apply them as questions in deposition rather than grounds for exclusion. Pre-deposition, generate a cross-exam question bank tailored to the witness's specialty and your case theory.
The Free Daubert Workup tool returns a specialty-tailored Daubert checklist + 40-60 cross-exam questions for any opposing expert. No signup required — just witness name, specialty, and your email.
Get Free Workup →John Mahoney is the founder of MedLegal AI. He builds AI tools for medical-malpractice plaintiff attorneys. Questions? [email protected]