Expert Testimony Admissibility: Federal vs. State Court

Federal courts apply a reliability-based gatekeeping framework (Daubert v. Merrell Dow Pharmaceuticals, Inc., 1993; Kumho Tire Co. v. Carmichael, 1999). The trial judge evaluates whether the expert's methodology is reliable and reliably applied to the case, considering factors such as testability, peer review and publication, known or potential rate of error, the existence of controlling standards, and general acceptance in the relevant field. The factors are non-exclusive and the analysis is case specific.

Some states apply a similar reliability framework to the federal courts. Other states retain a narrower general-acceptance framework that focuses on whether the methodology is generally accepted in the relevant scientific community (Frye v. United States, 1923). Several states have distinctive hybrid frameworks, sometimes codified by statute or rule.

Admissibility is decided at four points in a case, and the report is written with all four in view. At retention, the framework of the forum decides how the expert documents the method: an opinion headed for a gatekeeping court is prepared as if a pretrial motion will be filed. At disclosure, the report or statement served on the other side is the record the challenge will be built from; a basis the report does not state is a basis the court may not consider. At deposition, the questions that test foundation, sources and the application of the method to this person are asked with the motion in mind. At trial, the foundation questions on direct examination establish the qualification, the method and the data before the opinion is offered, and an objection at that point is decided on the same considerations.

Most challenges are raised by motion after the expert's deposition, on the schedule the court's order sets. Because the report and the deposition transcript are the evidence on that motion, an expert retained late, with a report written to a deadline and without the records the method calls for, is exposed at the stage where the exposure is hardest to cure. Attorneys are responsible for confirming the governing framework against primary sources at retention, not at the motion.

A report prepared for a gatekeeping forum shows its work on the page. It identifies the records and data reviewed, by name and date, so the sufficiency of the facts can be checked. It states the method in the terms the discipline uses and names the published references for it, so the court can see that the method is the field's and not the witness's own. It sets out the assumptions the opinion depends on, one by one, with the source for each, and where an assumption could reasonably be made differently it states the alternative and what it would do to the result. It then traces the reasoning from the data through the method to the conclusion, so the fit between the opinion and the facts of the case can be followed step by step.

The same report serves a general-acceptance forum without change. The method statement and the references answer the general-acceptance question directly, and the sources, assumptions and reasoning are what cross-examination will test. A report written to the narrower framework alone, with the method named but the data and the reasoning left implicit, is the one that has to be rewritten when the case moves or the challenge comes.

Vocational reports. The restriction set the opinion applies and the medical source of each restriction; the coding of past work and of the occupations identified, with the classification references used; the labor market evidence for those occupations, with the area and the date of the wage data; and the reasoning that connects the restrictions, the profile and the market to the earning capacity stated. The practitioner guide to the reliability framework for vocational experts lists the objections raised most often.

Economic reports. The base earnings and their source; the worklife horizon and the table it comes from; the growth and discount assumptions and the series behind them; the fringe benefit rate and its source; the household services and, in death cases, the personal consumption figures and their sources; and a sensitivity statement showing how the total moves with the principal assumptions.

Life care plans. The clinical foundation for each item, meaning the physician or other qualified recommendation and where in the record it appears; the frequency and duration of each item and the recommendation or literature that supports it; the cost source for each item and the geography it reflects; and the life expectancy used and whether it was adjusted. An item without a stated foundation is the element most often excluded, and its removal changes the total the economist projects.

For a federal case, the written report is the disclosure, so it is complete when served: opinions, bases, data, qualifications, prior testimony and compensation in the form the governing rule requires, which counsel confirm. The expert expects a deposition directed at the report and, if a motion follows, a hearing at which the method and its application are explained to the judge without the jury present.

For a state case, the form of disclosure follows the state's practice, which may be a report, an answer to an expert interrogatory signed by the expert, or a shorter statement, and the reliability question may be decided on the papers, at a pretrial hearing or at trial. The expert prepares the same underlying work product in every case and adapts the served document to the forum's format, so that the fuller report is available if the framework applied turns out to be the more demanding one. Where a case may be removed to federal court, or where the state's framework is unsettled, counsel and the expert plan for the gatekeeping inquiry from the start.

Always confirm the governing admissibility framework for the specific case against primary sources before preparing expert testimony. The framework can vary by case type, by court within the same state, and over time as state law evolves.