A Practicing Physician's Guide to Expert Witness Work

By John Mahoney · August 18, 2026

Most physicians learn what expert witness work involves only after an attorney calls them. This is the briefing that should exist beforehand — what the work actually is, what it demands, and how to tell whether it fits you.

What the work actually is

Strip away the courtroom imagery and the job is mostly reading.

A case arrives as records. Sometimes four hundred pages, sometimes eleven thousand. You read them the way you would read a consult you had unlimited time for, and you form an opinion about a specific question: was the care within the standard, and if it was not, did that failure cause this harm.

Then you write that opinion down. Then, in most cases that go anywhere, you sit for a deposition where an attorney whose job is to dismantle your reasoning asks you about it for several hours.

A small minority of cases reach trial. Most settle, and many resolve before you are ever deposed. Physicians who imagine this work as testifying have the ratio backwards — it is reading and writing, punctuated occasionally by being questioned.

The four things attorneys are actually screening for

Current practice. This is first and it surprises people. An expert whose clinical work is behind them gets attacked for exactly that, and the attack lands. If you are actively doing the thing at issue, you are more valuable than someone more senior who stopped doing it six years ago.

Current board certification. A lapse is a gift to opposing counsel. Keep it clean.

Routine familiarity with the specific issue. Not fame in the field — routine, hands-on familiarity. The question is always some version of "do you do this, regularly, now?"

The ability to be clear without being condescending. You are explaining medicine to people who did not go to medical school, in a setting where sounding arrogant costs you credibility and oversimplifying costs you accuracy. This is the filter that actually separates good experts from bad ones, and it has nothing to do with seniority.

Plaintiff, defense, or both

New experts often assume they must choose a side, and that choosing plaintiff makes them a traitor to colleagues while choosing defense makes them a shill.

The durable answer is to do both, and to be visibly willing to do both.

An expert who has only ever worked one side gets impeached with that fact in every deposition: Doctor, in fourteen years you have never once found that a physician met the standard of care, have you? The physicians with the longest careers in this work take cases from both directions and decline cases from both directions, which makes the question a non-event.

It also keeps you honest, which is the actual point. Your obligation is to the standard of care as you understand it, not to whoever sent the retainer.

How cases find you

Mostly through directories, referrals from other physicians who do this work, and attorneys who found you through prior testimony or publication. Expert-witness directories are the common entry point.

Attorneys are generally looking for someone specific — the right subspecialty, the right state, no disqualifying conflicts — which means the more precisely your listing describes what you actually do, the better the matches. Vague listings generate irrelevant calls.

The first case is the hardest to get. After that, attorneys talk to each other.

What the schedule really looks like

Lumpy. A case arrives, consumes a concentrated block of reading time, then goes quiet for months while the litigation grinds. Then a deposition gets scheduled with several weeks' notice.

Depositions are usually scheduled around your availability — you are the retained expert, and attorneys accommodate. Trial testimony is far less flexible, but far less common.

The practical implication: this fits around clinical practice better than most second occupations, but it is not evenly distributed. Some months are nothing; some weeks are heavy.

The obligations nobody advertises

Neutrality is not optional and not merely ethical — it is protective. The moment you start advocating, you become both a worse expert and a much easier witness to damage. Opposing counsel will find every place you strained.

You have to be willing to say a case has no merit, after you have been paid to review it, to the attorney who hired you. This happens regularly. It is the single clearest marker of an expert worth retaining, and attorneys who plan to keep working with you respect it.

Everything you write is discoverable. Notes, drafts, marginalia, emails. Write every word as though it will be read aloud to you slowly by someone unfriendly, because it may be.

Your prior testimony follows you. Statements you made in a different case, on a different fact pattern, will be produced and compared to what you are saying now. Consistency across years matters more than cleverness in any one case.

Your CV will be scrutinized harder than it has ever been. Every claim on it, checked. Round nothing up.

Daubert, in plain language

You will hear this word constantly. The short version: a court can exclude expert testimony that is not grounded in reliable methodology, and opposing counsel may file a motion arguing that yours is not.

What it means practically is that your opinion needs a traceable path from the record and the literature to your conclusion — not "in my experience, this was negligent," but a stated basis someone else could follow and evaluate. Opinions that rest on nothing but personal authority are the ones that get challenged.

For most physicians writing carefully within their own specialty, this is a discipline rather than a hazard. It is also, not incidentally, the same discipline that makes the work improve your clinical reasoning.

Preparing for the first deposition

The medicine is rarely the problem. The format is.

A deposition inverts the instincts that make you a good clinician. When a question is vague in clinic, you fill the gap and help; in a deposition, that is how you end up testifying to something you never meant. Silence in clinic is something you fill; in a deposition it is a technique being used on you. "It depends" is honest and complete in clinic; in a deposition it is an opening.

Your teaching impulse, your thoroughness, your wish to be understood — all of them are liabilities in a room designed to convert them.

None of this is knowledge you lack. It is a format you have never practiced under pressure, run by someone who has done it a thousand times. Which is the entire argument for rehearsing it before it counts, against the same techniques the other side will actually use.

Is it for you?

The honest test is not whether you want additional income. It is whether the following sounds appealing or exhausting: reading a complete medical record closely, forming a defensible opinion about it, writing that opinion in careful language, and then defending every sentence to someone trying to take it apart.

Physicians who find that appealing tend to find the work deeply engaging, and tend to say — with some surprise — that it made them better at their day job.

Physicians who find it exhausting should not do it, and there is no shame in that. There are easier ways to earn money. There are very few that make you better at medicine while you do it.