Expert Witnesses in Head Injury Cases

Quick answer

Head injury cases usually depend on expert testimony from physicians, neuropsychologists or neuroradiologists. In federal court, Rule 702 allows expert testimony only if the party offering it shows the court “it is more likely than not” that the testimony is helpful, based on sufficient facts, reliable methods and a reliable application of those methods.[1] The Daubert standard applies in all federal courts, while some state courts still use the older Frye standard.[2]

Federal Rule of Evidence 702

Federal Rule of Evidence 702

A witness who is qualified as an expert by knowledge, skill, experience, training, or education may testify in the form of an opinion or otherwise if the proponent demonstrates to the court that it is more likely than not that: (a) the expert’s scientific, technical, or other specialized knowledge will help the trier of fact to understand the evidence or to determine a fact in issue; (b) the testimony is based on sufficient facts or data; (c) the testimony is the product of reliable principles and methods; and (d) the expert’s opinion reflects a reliable application of the principles and methods to the facts of the case.

Source: [1]

The Daubert standard

In Daubert v. Merrell Dow Pharmaceuticals (1993), the U.S. Supreme Court held that “the trial judge must ensure that any and all scientific testimony or evidence admitted is not only relevant, but reliable.”[3] LII summarizes the factors courts consider:[2]

  1. Whether the technique or theory can be, and has been, tested
  2. Whether it has been subjected to publication and peer review
  3. Its known or potential error rate
  4. The existence and maintenance of standards controlling its operation
  5. Whether it has attracted widespread acceptance within a relevant scientific community

The Frye standard

The Frye standard comes from Frye v. United States, 293 F. 1013 (D.C. Cir. 1923).[4] LII explains that it focused primarily on whether scientific evidence is generally accepted in its field, and that “while some state courts still adhere to the Frye Standard, the Daubert Standard is used in all federal courts.”[2]

Common experts in head injury cases

Neurologists

Diagnosis, causation and prognosis.

Neuropsychologists

Cognitive testing and validity.

Neuroradiologists

Interpretation of CT, MRI and DTI.

Physiatrists

Rehabilitation and functional limits.

Life care planners

Future care needs and costs.

Economists

Lost earning capacity.

Where challenges arise

Expert challenges in head injury cases often involve newer methods, such as DTI, where the literature is divided on reliability in mild TBI.[5][6] See advanced imaging. Neuropsychological opinions may also be challenged on whether validity was addressed, which professional guidance says every forensic evaluation must do.[7]

Frequently asked questions

What changed in Rule 702 in 2023?

The current rule requires the proponent to demonstrate to the court that it is “more likely than not” that each requirement is met.[1]

Does my state use Daubert or Frye?

It varies. Daubert applies in all federal courts, and some state courts still use Frye.[2]

This page provides general information about the law from the sources listed below. It is not legal advice, and reading it does not create an attorney-client relationship. Laws vary by state and change over time. See our legal disclaimer.

Sources

  1. Federal Rules of Evidence, Rule 702. Legal Information Institute. https://www.law.cornell.edu/rules/fre/rule_702
  2. Legal Information Institute, Wex. “Daubert standard.” https://www.law.cornell.edu/wex/daubert_standard
  3. Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993). Legal Information Institute. https://www.law.cornell.edu/supremecourt/text/509/579
  4. Legal Information Institute, Wex. “Frye standard.” https://www.law.cornell.edu/wex/frye_standard
  5. Wortzel HS, Kraus MF, Filley CM, Anderson CA, Arciniegas DB. “Diffusion Tensor Imaging in Mild Traumatic Brain Injury Litigation.” Journal of the American Academy of Psychiatry and the Law, 2011;39(4):511-523. https://jaapl.org/content/39/4/511
  6. van Velkinburgh JC, Herbst MD, Casper SM. “Diffusion tensor imaging in the courtroom: Distinction between scientific specificity and legally admissible evidence.” World Journal of Clinical Cases, 2023. https://pubmed.ncbi.nlm.nih.gov/37469746/
  7. Sweet JJ, et al. “American Academy of Clinical Neuropsychology (AACN) 2021 consensus statement on validity assessment.” The Clinical Neuropsychologist, 2021;35(6):1053-1106. https://pubmed.ncbi.nlm.nih.gov/33823750/

Sources last checked: October 11, 2026

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