Me. Rev. Stat. tit. 25, § 1503

Members of the State Police must be provided at the expense of the State with a distinctive uniform and badge, and with suitable equipment, all of which remains the property of the State. When on duty to enforce the laws of the road, and at such other times as the Chief of the State Police may require, members of the State Police shall be in uniform. It is unlawful for any person to wear the prescribed uniform or badge of the State Police or any distinctive part of that uniform, except on order of the Chief of the State Police.