Utah Code § 39A-4-112: Governor may proclaim martial law.

(1) Whenever the Defense Force or any portion of the Defense Force is called into active service, the governor may, by proclamation, declare all or any part of any county, city or town in which the troops are serving to be under martial law.

(2) When the Defense Force is in active service, the commanding officer and his subordinates may cooperate with the civil authorities as directed by the adjutant general.