How Actuarial Expert Witnesses Get Excluded Under Daubert — and How to Survive the Cross

Daubert is not a medicine problem. Under Kumho Tire and the 2023 amendment to Federal Rule of Evidence 702, the trial court's gatekeeping applies to every form of specialized testimony — actuarial included. A 20-year study of 2,842 challenges to non-medical experts found that roughly half of those opinions were excluded or partially excluded, and the single most-cited reason was “unreliable methodology.”

The exclusion rarely happens in a written motion alone. It is built, piece by piece, in the deposition cross-examination — where opposing counsel walks a actuarial expert into conceding scope, methodology, or an assumption that unravels the whole opinion. Here are the three traps, and how a prepared expert answers each one.

The three ways actuarial experts lose ground

Scope: testifying outside your lane

The cross-examiner's question sounds simple:

Your projection used a discount rate and mortality table you selected — different choices change the result, don't they?

Why it works: The ASOP assumptions are the actuary's anchor — disclose every assumption and show sensitivity.

A stronger answer: “I used assumptions consistent with the applicable Actuarial Standards of Practice, disclosed each, and presented sensitivity to reasonable alternatives.”

Methodology: the reliability attack

The cross-examiner's question sounds simple:

Your reserve opinion relied on the company's data — you didn't independently audit it, did you?

Why it works: Methodology / data reliance under the ASOPs.

A stronger answer: “I relied on the data per the ASOP on data quality, performed reasonableness checks, and disclosed any reliance and its limits.”

Assumptions: the one premise that sinks the opinion

The cross-examiner's question sounds simple:

You assume current trends continue — but the future is uncertain, isn't it?

Why it works: The trend-continuation assumption. Present ranges.

A stronger answer: “I disclosed the trend assumptions and presented ranges rather than a single deterministic figure.”

How to prepare for the cross before you're sworn in

Every one of those traps is defeatable — but not by reading your report one more time. The experts who survive the cross have done three things:

• Rehearsed the cross-examination out loud, repeatedly, against a realistic examiner — so the scope concession, the methodology defense, and the assumption hedge are second nature.
• Mastered the record, so that when counsel asks them to recall the one line buried in thousands of pages of the policy data, mortality tables, and assumptions, they can produce it in seconds rather than fumble.
• Stress-tested the report against FRE 702 — finding the reliability gaps before opposing counsel does.

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