Expert Witnesses in South Dakota
In South Dakota, an expert witness is not defined by a separate standalone statute but is understood through S.D. R. Evid. 19-19-702, which mirrors Federal Rule 702. In other words, an expert witness in South Dakota is a qualified specialist who can provide opinion testimony to help the court understand complex or technical matters, provided the testimony is reliable and relevant.
Rules Governing Disclosure
South Dakota’s § 15-6-26 emphasizes discovery of expert opinions, protects drafts and most attorney-expert communications, and imposes an ongoing duty to supplement expert-related disclosures.
South Dakota follows a broad discovery approach, permitting parties to obtain detailed information about opposing experts through Rule 26 mechanisms. This ensures that expert testimony is tested before trial, not sprung as a surprise.
A party intending to use expert testimony at trial must disclose:
Identity of the expert: Name and role of each expert expected to testify; area of expertise and subject matter of testimony;
Substance of opinions: The expert’s opinions and conclusions; the scope of testimony the expert intends to offer;
Facts and data considered: All materials, data, and information the expert reviewed or relied upon, including documents, studies, records, and other inputs.
Admissibility Standards
South Dakota follows a reliability-focused (Rule 702–type) approach based on Daubert, allowing expert testimony when it will help the trier of fact understand the evidence or determine a fact in issue.
Expert testimony must meet certain standards:
Be based on sufficient facts or data
Be the product of reliable principles and methods
Reflect a reliable application of those methods to the case
Attorney–Expert Communication Protection
While South Dakota protects the collaborative process between attorney and expert, it requires disclosure of anything that shapes the substance or credibility of the expert’s opinion. For instance:
Exceptions (Not Protected / Discoverable):
Compensation:
Any communication regarding the expert’s fees, billing structure, or payment terms is discoverable, ensuring transparency regarding potential bias or financial incentive.Facts or Data Provided by Counsel:
Materials, documents, or information provided by the attorney that the expert considered must be disclosed. The focus is on what influenced the expert’s opinion, not merely what was sent.Assumptions Provided by Counsel:
Hypothetical or factual assumptions supplied by the attorney and relied upon by the expert are discoverable. This is critical where experts base opinions on case-specific scenarios framed by counsel.
Compensation
South Dakota requires experts to be paid reasonable, transparent fees—borne by the retaining party (and by the opposing party for depositions)—while prohibiting arrangements that compromise impartiality.
Limits on Number of Expert Witnesses
South Dakota places no fixed cap on expert witnesses, but courts retain discretion to limit excessive or duplicative experts to ensure efficient and fair proceedings.
Out-of-State Expert Qualification
South Dakota does not require experts to be in-state—out-of-state experts may testify if they meet general qualification and reliability standards.
State-Specific Statutes & Local Rules
S.D. Codified Laws § 15-6-26: Expert disclosure requirements
S.D. R. Evid. 19-19-702: Admissibility of expert testimony
