Minn. Stat. § 628.65: MAKE DISCLOSURE, WHEN.

Any grand juror may be required by any court to disclose the testimony of any witnesses examined before the grand jury, for the purpose of ascertaining whether it is consistent with that given by the witnesses before the court, or to disclose the testimony given before it by any other person, upon a charge against the person for perjury in giving the testimony, or upon the trial therefor.