Expert Witnesses in Idaho
In Idaho courts, an expert witness is someone whose specialized expertise allows them to provide opinions that ordinary witnesses cannot. Their role is to explain complex subjects and help the jury or judge understand technical issues.
Rules Governing Disclosure
In Idaho, expert witness disclosures are governed primarily by Idaho Rule of Civil Procedure 26. Retained experts do require a fairly detailed disclosure, while non-retained experts get a shorter summary disclosure. A retained or specially employed expert must disclose:
a complete statement of all opinions and the basis and reasons for them,
the data or other information considered,
any supporting or summary exhibits,
the expert’s qualifications, including publications from the prior 10 years,
the expert’s compensation, and
a list of other cases in which the expert testified at trial or by deposition during the prior 4 years.
By contrast, for non-retained experts—such as treating physicians or other witnesses whose knowledge was not developed for litigation—the disclosure is lighter. Idaho requires only:
the subject matter of the expected testimony, and
a summary of the facts and opinions to which the witness is expected to testify.
Idaho Rule of Civil Procedure 37 provides a strong enforcement mechanism for the disclosure requirements in Idaho Rule of Civil Procedure 26. If a party fails to identify an expert witness or fails to provide the required expert disclosure information, the party is generally not allowed to use that witness or information at trial, at a hearing, or in a motion, unless the failure was substantially justified or harmless.
Admissibility Standards
In Idaho, the admissibility of expert testimony is governed primarily by Idaho Rule of Evidence 702, which reflects the reliability principles articulated in Daubert v. Merrell Dow Pharmaceuticals, Inc.. Idaho courts therefore apply a Daubert-style reliability framework when determining whether expert testimony should be admitted.
Under this approach, the trial judge acts as a gatekeeper and must determine whether the expert’s testimony is both relevant and reliable before it can be presented to the jury. The focus of the court’s inquiry is on the principles and methodology used by the expert rather than the ultimate conclusions reached.
Attorney–Expert Communication Protection
Communications between an attorney and a testifying expert are generally protected from disclosure, regardless of their form. However, three categories remain discoverable: communications regarding the expert’s compensation, facts or data provided by the attorney that the expert considered, and assumptions supplied by the attorney that the expert relied upon when forming opinions.
For consulting experts who are retained only for trial preparation and are not expected to testify, their opinions and knowledge are ordinarily not discoverable. Discovery is permitted only in limited situations—such as under Rule 35(b) or when a party demonstrates exceptional circumstances making it impracticable to obtain the same information by other means.
Compensation
In Idaho, expert witnesses are typically paid by the party who retains them, while the party seeking discovery from the expert—such as by deposition—must pay a reasonable fee for the expert’s time spent responding to that discovery. Courts retain authority to ensure that such fees are fair and reasonable under the circumstances.
Limits on Number of Expert Witnesses
Idaho does not place a formal cap on expert witnesses, but trial courts can effectively limit the number of experts through scheduling orders and by excluding repetitive testimony to ensure efficient and fair proceedings.
Out-of-State Expert Qualification
Idaho does not impose special restrictions on out-of-state expert witnesses. As long as the expert satisfies the qualification requirements of Rule 702 and possesses relevant expertise—particularly familiarity with applicable professional standards—the expert may testify regardless of where they are located.
State-Specific Statutes & Local Rules
I.R.C.P. 26: Controls expert discovery and deposition process
I.R.C.P. 37: Provides for sanctions for failure to disclose experts properly
I.R.E. 702: Admissibility of expert witness testimony
