Minn. Stat. § 357.29: SERVICES NOT RENDERED; ILLEGAL FEES.

No judge, sheriff, or other officer, or any other person to whom any fee or compensation is allowed by law for any service, shall take or receive any other or greater fee or reward for the service than allowed by law. No fee or compensation shall be demanded or received by any officer or person for any service unless it was actually rendered, except in the case of prospective costs. Any person violating either of these provisions is liable to the party aggrieved for treble the damages sustained.