Expert Witnesses in Minnesota
Under Minnesota Rule of Evidence 702, an expert witness is a witness who is qualified by knowledge, skill, experience, training, or education and whose specialized testimony will assist the trier of fact in understanding the evidence or determining a fact in issue.
Rules Governing Disclosure
Rule 26.01(b) of the Minnesota Rules of Civil Procedure imposes mandatory disclosure obligations for expert witnesses, distinguishing between retained experts and non-retained experts, and prescribing the content, timing, and consequences of those disclosures.
For experts retained or specially employed to provide expert testimony, disclosure must include a written report, prepared and signed by the expert, containing:
A complete statement of all opinions the expert will express;
The basis and reasons for those opinions;
The facts or data considered in forming the opinions;
Any exhibits that will be used to summarize or support the opinions;
The expert’s qualifications, including a list of publications authored in the previous 10 years;
A list of cases in which the expert testified as an expert at trial or by deposition in the preceding 4 years;
A statement of compensation to be paid for the study and testimony.
For experts not retained or specially employed (e.g., treating physicians, fire investigators, code officials), disclosure must state:
The subject matter on which the witness is expected to present evidence under Minnesota Rule of Evidence 702, 703, or 705; and
A summary of the facts and opinions to which the witness is expected to testify.
Minnesota continues to require ongoing supplementation of expert disclosures under Rule 26.05 when new information, opinions, or changes occur after initial disclosure — emphasizing the need to keep expert information accurate and complete throughout discovery.
Also, Minn. Stat. § 145.682 governs expert-related affidavits in medical malpractice lawsuits — not general civil expert disclosures, but specific affidavit requirements designed to screen out meritless malpractice claims. This affidavit confirms that an expert has preliminarily evaluated the case and believes there is a viable malpractice claim. Failure to timely provide the detailed expert identification affidavit within the 180-day (after discovery) deadlines also leads to dismissal if not corrected. Non-compliance can result in mandatory dismissal with prejudice, so meeting and documenting these deadlines is critical in Minnesota medical malpractice litigation.
Timing
Under Rule 26.01(b)(4)–(5) of the Minnesota Rules of Civil Procedure, a party must disclose expert testimony at the times and in the sequence ordered by the court. If there is no court order or stipulation setting the schedule, expert disclosures must be made at least 90 days before the date set for trial or for the case to be ready for trial. Expert evidence intended solely to contradict or rebut another party’s expert disclosure on the same subject matter must be disclosed within 30 days after the opposing party’s disclosure. In addition, parties have a continuing obligation to supplement expert disclosures as required by Rule 26.05 when the information disclosed is incomplete or incorrect.
Admissibility Standards
In Minnesota, expert testimony is governed primarily by Minnesota Rule of Evidence 702, which requires that the witness be qualified by knowledge, skill, experience, training, or education, and that the testimony assist the trier of fact. Expert opinions must be based on a reliable foundation—Minnesota uses a hybrid Frye–Mack standard, meaning that the underlying scientific principles must be generally accepted in the relevant field (the Frye requirement) and the expert’s methodology must be reliable as applied to the facts of the case (the Mack requirement). Even where reliability is established, Rule 403 authorizes courts to exclude expert evidence if its probative value is substantially outweighed by risks such as unfair prejudice, confusion, or needless delay. Rule 705 allows experts to offer opinions without first detailing the underlying facts, but those bases must be discoverable and are subject to cross-examination. Together, these rules give Minnesota courts broad gatekeeping authority to ensure that expert testimony is properly grounded in expertise, methodologically sound, and helpful to the jury, while filtering out unsupported or speculative opinions.
Attorney–Expert Communication Protection
Under Minn. R. Civ. P. 26.02, attorney mental impressions, strategies, and legal theories are protected work product. This protection extends even if conveyed to a testifying expert. Minnesota protects communications between lawyers and testifying experts to an extent, but not as strongly as the federal rules. However, Minnesota allows discovery into facts, data, or assumptions provided by the counsel if the expert relied on them in forming opinions.
Compensation
Minnesota Statute § 357.25 authorizes courts to award reasonable expert witness fees as part of the costs recoverable at the end of a lawsuit.
In Minnesota, expert witness fees are set through private negotiation, subject to the requirement that compensation be reasonable and proportionate. The rates are typically based on hourly or flat fees covering record review, report preparation, deposition and trial testimony, travel time, and related expensesThe party retaining the expert is responsible for paying those fees, and Minnesota Rule of Civil Procedure 26.02(d)(3) further requires that the party seeking to depose the opposing party’s expert must pay a reasonable fee for the expert’s time spent responding to discovery, although courts may intervene if the fee is disputed or appears excessive.
Limits on Number of Expert Witnesses
Minnesota does not impose a statutory limit on the number of expert witnesses a party may call at trial. Instead, the number of experts is governed by relevance and trial court discretion rather than a fixed cap. Under the Minnesota Rules of Evidence, a court may restrict testimony that is cumulative, repetitive, or unduly time-consuming, and judges routinely use this authority to prevent multiple experts from offering duplicative opinions on the same issue.
Out-of-State Expert Qualification
In Minnesota, the court evaluates whether the expert is qualified by education, training, skill, or experience under Minn. R. Evid. 702, regardless of where they live or work.
To be admitted, the expert must:
Have the necessary professional credentials,
Be familiar with the subject matter they are testifying about, and
(In medical malpractice cases) be knowledgeable about the standard of care in a similar practice or locality, even if they do not practice in Minnesota.
Rebuttal Experts
Minnesota recognizes rebuttal experts, but their use and disclosure are controlled by the Minnesota Rules of Civil Procedure and, most importantly, the court’s scheduling order. Although there is no stand-alone rule governing rebuttal experts, they must still be disclosed in accordance with Rule 26’s expert-disclosure and supplementation requirements, and courts typically set a specific rebuttal-expert deadline that follows the initial expert-disclosure date.
State-Specific Statutes & Local Rules
Minn. Stat. § 145.682: Governs expert disclosure in medical malpractice actions
Minn. R. Civ. P. 26.01(b): Lays out expert disclosure requirements
Minn. R. Evid. 702: Establishes the admissibility criteria for expert testimony
