S.D. Codified Laws § 36-1-3

This chapter shall operate retroactively and any person within the class named herein practicing or engaged in any profession, trade, science or business on July 1, 1947, shall be deemed to have been fully restored and reinstated to the status existing on the date of induction or enlistment into the armed forces and any act or thing done by any department, state board, commission, agency, or officer restoring and reinstating such person to such status is hereby validated and legalized.