S.D. Codified Laws § 32-33-1
The county highway superintendent of each organized county shall have authority to act in the capacity of a peace officer within the boundaries of the county in which he holds office, for the purpose of enforcement of all license and loading laws and traffic regulations governing the highways of the state, and shall have authority to stop any and all vehicles as defined in § 32-14-1 for the purpose of examining or measuring the form or for weighing the loads transported thereon, and may place violators of the provisions of this title under arrest without warrant for offenses committed in his presence, and take any violator of the provisions of this title and any vehicle which does not conform to any provisions of this title or of the registration or license laws, to the nearest convenient circuit or magistrate court for trial at the earliest opportunity, and the court shall impound any offending vehicle and not permit the same to be driven until it shall be made to conform to the laws relating to licensing and registration and also the provisions of this title relating to lighting, loading, and size.
SDCL 32-33-1