How Economic Damages 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 — economic damages 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 economic damages 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 economic damages experts lose ground

Scope: testifying outside your lane

The cross-examiner's question sounds simple:

You're an economist, not a vocational expert — yet your model assumes the plaintiff can't return to work, correct?

Why it works: The inputs-vs-opinion scope line. Model the loss on others' inputs; don't opine outside economics.

A stronger answer: “I model the economic loss given the vocational and medical inputs provided by those experts; I don't opine on employability myself, and I disclosed the inputs I relied on.”

Methodology: the reliability attack

The cross-examiner's question sounds simple:

Your lost-earnings figure used a growth rate and a discount rate you selected — different choices change the number substantially, don't they?

Why it works: Discount/growth-rate methodology — the economist's exclusion driver. Source the rates and show sensitivity.

A stronger answer: “I used accepted, sourced rates and presented a sensitivity analysis showing the effect of reasonable alternatives, rather than a single figure.”

Assumptions: the one premise that sinks the opinion

The cross-examiner's question sounds simple:

You assume the plaintiff would have worked to age 67 — you have no proof of that, do you?

Why it works: The worklife assumption. Use worklife tables and present the range.

A stronger answer: “I used published worklife-expectancy tables and disclosed the assumption transparently, with alternatives, rather than assuming a fixed retirement age.”

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 earnings records, tax returns, and projections, 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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