How Electrical Engineering 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 — electrical engineering 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 electrical engineering 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 electrical engineering experts lose ground

Scope: testifying outside your lane

The cross-examiner's question sounds simple:

You opine the wiring violated the National Electrical Code — but you weren't licensed in this jurisdiction at the time of installation, correct?

Why it works: The scope/qualification attack. Ground the opinion in the code sections and your competence to read them.

A stronger answer: “Correct. The NEC is a national standard I apply by training and experience; jurisdictional licensure doesn't change the code analysis, and I cited the specific sections.”

Methodology: the reliability attack

The cross-examiner's question sounds simple:

Your conclusion relied on the as-found condition — but the panel was de-energized and partially disassembled before your inspection, wasn't it?

Why it works: Methodology / spoliation-of-condition. Separate what you observed from what you inferred about the original state.

A stronger answer: “Yes. I documented the as-found condition I observed and relied on the pre-disturbance photos and reports for anything altered before my inspection, and I noted that limit.”

Assumptions: the one premise that sinks the opinion

The cross-examiner's question sounds simple:

You assumed the ground-fault protection was never tested — but the maintenance log you didn't review may show otherwise, correct?

Why it works: The records-gap assumption. Bound your opinion to what you reviewed and don't assume the absence of a record you never looked for.

A stronger answer: “My opinion is based on the records I was provided; if additional maintenance logs exist I would review them, and I flagged that my analysis is bounded by the available records.”

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 schematics, code records, and inspection reports, 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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