Different rules apply to the disclosure of witnesses depending on whether the case regards a felony/gross misdemeanor or misdemeanor. However, it is safest to take the position that regardless of the level of the offense, an attorney is required to disclose the witness as well as the substance of what the witness is going to say at trial. In the case of an expert, it’s also important to provide their curriculum vitae or other information about the expert’s qualifications.
Minn.R.Crim.P. 9.02 controls the requirements for the Defendant’s disclosures in felony and gross misdemeanor cases. Specifically, Subd. 1 (2)(b) states:
In addition, a person who will testify as an expert but who created no results or reports in connection with the case must provide to the defense for disclosure to the prosecutor a written summary of the subject matter of the expert’s testimony, along with any findings, opinions, or conclusions the expert will give, the basis for them, and the expert’s qualifications.
This rule requires that you not only to disclose the witness, their qualifications (i.e. curriculum vitae) but also basically what they are going to say at trial.
There is no corresponding rule for misdemeanor discovery. As a matter fact, beyond the prosecutor providing the police reports, Minn.R.Crim.P. 9.04 merely states, “Any other discovery must be by consent of the parties or by motion to the court.” While this may be what the rule says, a judge would be loath to allow the defense to call any witnesses that have not been disclosed to the prosecutor, especially an expert witness. It’s a good practice to treat misdemeanor disclosures similar to felony and gross misdemeanor disclosures.
Remember that the proponent of any evidence (whether an expert or otherwise) must be able to fulfill all the requirements that make the evidence admissible such as relevancy, foundation, etc. If you think there may be an issue as to the proffered testimony, it may be worthwhile to bring it up ahead of time. Simply because the opposing party doesn’t object before the witness is called doesn’t mean that an objection would not be timely or appropriate once he witness attempts to testify.