Mont. Code Ann. § 19-17-604

The board may require a member who receives a disability benefit to undergo periodic medical examinations. The examinations must be made by a board-approved physician or surgeon at a place mutually agreeable to the board, the physician or surgeon, and the member and at the board's expense. Upon the basis of these examinations and the advice of the board's consulting physician, the board shall determine, by reason of physical or mental capacity, whether the member remains permanently and totally disabled.