Expert disclosure · Federal practice

FRCP 26(a)(2)(B): what an expert's report — and its 4-year testimony list — must contain

A retained expert's written report is the document opposing counsel will use to box you in. Here is exactly what Rule 26 requires it to contain, why the 4-year prior-testimony list does more damage than experts expect, and how to keep every element current and defensible.

If you are a retained or specially-employed expert in federal civil litigation, Federal Rule of Civil Procedure 26(a)(2)(B) governs your written disclosure. It is not optional and it is not a formality: an incomplete report can get your testimony limited — or excluded — under Rule 37(c)(1), no matter how qualified you are. The report is what the jury's exposure to your opinion ultimately runs through.

This guide breaks the rule into its six required elements, explains the two list requirements that experts most often get wrong (the 4-year testimony list and the 10-year publication list), and shows how to keep the whole package defensible without rebuilding it from scratch on every engagement.

The six things a Rule 26(a)(2)(B) report must contain

For any witness "retained or specially employed to provide expert testimony," the report must be prepared and signed by the witness and contain:

1. A complete statement of all opinions the witness will express — and the basis and reasons for them. "Complete" is the operative word: opinions not disclosed here generally cannot be offered at trial.
2. The facts or data considered by the witness in forming those opinions. Note "considered," not merely "relied upon" — it is broader than many experts assume.
3. Any exhibits that will be used to summarize or support the opinions — charts, demonstratives, and yes, the chronology or timeline you build from the record.
4. The witness's qualifications, including a list of all publications authored in the previous 10 years.
5. A list of all other cases in which the witness testified as an expert — at trial or by deposition — during the previous 4 years.
6. A statement of the compensation to be paid for the study and testimony in the case.

The 4-year testimony list: where careful experts still get hurt

Element five looks clerical. It is not. The list of cases in which you testified — at trial or by deposition — in the preceding four years is a gift to a prepared cross-examiner, and it does two distinct kinds of work:

• Impeachment by inconsistency. Opposing counsel pulls your prior reports and transcripts and looks for any case where you described the same methodology differently, reached a contrary conclusion on similar facts, or used language that cuts against your current opinion. If your causation framework in this case reads differently than it did two years ago, expect to be asked why.
• The bias / "hired gun" narrative. A list weighted heavily toward one side — all plaintiff, all defense — combined with the compensation disclosure in element six, lets counsel build a financial-bias argument before you have said a word about the medicine.

The practical failure mode is mundane: experts reconstruct this list from memory or an old spreadsheet the night before the deadline, miss a deposition, and then get impeached not on the substance but on the accuracy of their own disclosure. An omission here reads as carelessness at best and concealment at worst — and it is entirely avoidable.

Keep it as a living record, not a deadline scramble

The 4-year list and the 10-year publication list are both cumulative, slow-moving records that should be maintained continuously across engagements — appended to the moment a deposition or trial concludes, not reconstructed per case. The same is true of your CV. Treat these as standing documents and the disclosure becomes a one-click export instead of a source of risk.

Why the underlying chronology matters to the report

Elements one and two — your opinions and the facts you considered — rest on your reading of the record. In a medical or personal-injury case, that means a defensible chronology: every material event tied to the page it came from, with conflicts and gaps surfaced rather than smoothed over. When each fact in your report can be traced to a source page, your "basis and reasons" survive contact with cross-examination. When it cannot, the gap is exactly where a Daubert challenge lives. (For how to build one, see our companion guide on building a defensible medical-record chronology.)

A quick pre-disclosure checklist

• Every opinion you intend to offer is stated here, with its basis — nothing held back for trial.
• The facts/data section reflects everything considered, including materials you ultimately set aside.
• Your chronology and demonstratives are attached as exhibits and each fact cites its source page.
• The 4-year testimony list is complete to the day — every trial and every deposition.
• The 10-year publication list and CV are current.
• Compensation is stated. The report is signed by you.