What the rule actually requires

Rule 26(a)(2)(B) sets out what a written expert report must contain. The fifth item is a list of all other cases in which, during the previous four years, the witness testified as an expert at trial or by deposition.

That is the whole requirement. It is one sentence, and it produces more last-minute scrambling than almost anything else in an expert engagement.

Why it is harder than it looks

The requirement sounds trivial until you try to satisfy it. An expert who testifies six or eight times a year has to reconstruct twenty-five or thirty appearances from calendars, invoices and memory, usually in the days before a report is due.

The reconstruction is where the problems start. Diary entries record the date you travelled, not necessarily the date you testified. Invoices record when you billed. A deposition that was noticed, postponed and taken three months later leaves two entries and one event. And a case that settled after your deposition may not be memorable at all — but it still belongs on the list.

An incomplete list is not a trivial oversight. It gives opposing counsel a straightforward line: you were required to disclose your testimony history, and what you disclosed was wrong. That conversation is about your reliability, not about the omitted case.

What counts as having testified

The rule says testimony at trial or by deposition. In practice a few situations sit at the edges, and they are worth raising with retaining counsel rather than deciding alone.

• Depositions in cases that settled. You testified. It counts, whatever happened afterwards.
• Depositions where you were never designated. If you gave deposition testimony as an expert, the plain words of the rule capture it.
• Affidavits and declarations. These are not testimony at trial or by deposition on the face of the rule. Many experts list them anyway, or note them separately, on the view that disclosing more is safer than disclosing less.
• Arbitrations and administrative hearings. Not obviously within “trial or by deposition”, but frequently included. Practice varies, and some courts’ standing orders ask for more than the rule does.
• Testimony in another jurisdiction. The rule does not limit the list to federal cases. State court testimony belongs on it.

The safe approach is to record everything as it happens, with enough detail to decide later. It is easy to leave an entry off a list. It is impossible to add one you never wrote down.

What to record for each appearance

The rule does not prescribe a format, and courts accept a range of them. What makes a list usable is that each entry identifies the case well enough for someone else to find it.

The last of those is not required by the rule, and some experts leave it out. Including it is usually the better choice: it will be asked in any event, and a list that already answers the question reads as candid rather than guarded.

Measuring the four years

The window runs backwards from the disclosure, not from the date you started work and not from the calendar year. An appearance four years and one week before your report falls outside it. An appearance four years less a day falls inside.

This matters more than it sounds when a case runs long. A report served in January covers a different window from a supplemental report served the following December, and an entry that was properly on the first list may properly drop off the second. If you are asked why the two differ, the answer is that the window moved — but you need to be able to say so with confidence.

The question behind the question

The list serves a disclosure purpose. It also hands opposing counsel a ready-made summary of your practice, and they will read it for patterns before they read it for completeness.

The pattern they are looking for is imbalance. If nineteen of your twenty appearances were for plaintiffs, that is the first thing raised, and it is raised as a question about independence rather than expertise. The same applies to concentration: if most of your work comes from one firm, expect to be asked what proportion of your income that represents.

Neither fact is improper. Plenty of respected experts work predominantly for one side, often because of the nature of their field. What damages credibility is being unable to answer, or giving a figure that the list then contradicts. Knowing your own numbers before the deposition turns a difficult moment into a straightforward one.

A short checklist

1. Record every appearance on the day, while the details are exact.
2. Note the date you testified, separately from travel or billing dates.
3. Keep edge cases — affidavits, arbitrations — in your records and decide with counsel whether to list them.
4. Measure the four years from the disclosure date, not the calendar year.
5. Check the finished list against your own invoices before it is served.
6. Know your plaintiff and defence split before you are deposed.

This page describes the position under the Federal Rules of Civil Procedure. Standing orders, local rules and the directions in your own case may require more than the rule does, and state courts differ. It is general information, not legal advice — confirm what your case requires with retaining counsel.