S.D. Codified Laws § 15-12-21.1

Prior to filing an affidavit for change of judge, the party or his attorney shall informally request the judge or magistrate who, in the ordinary course, would preside at the hearing or trial, to disqualify himself. He shall not be required to state his reasons, but may if he desires. Informally shall mean by letter, oral communication, or dictating it into the record in open court or chambers; however, the opposing parties should receive copies of any letters, or be apprised of any communications to the court, but cannot contest the request. If the judge or magistrate grants the request, he shall forthwith notify the presiding judge, who shall assign the case to some other judge or magistrate. If the judge refuses the request, he shall forthwith notify in writing the parties or their attorneys. Writing may include a letter, order, or dictation into the record.