S.D. Codified Laws § 27A-15-12
A parent who consented to a minor's admission under this chapter has the right to effect an immediate discharge of the minor upon written notice of the parent's intention to terminate inpatient treatment, unless the facility director, administrator, or attending psychiatrist has probable cause to believe the minor requires emergency intervention under § 27A-15-30 and should remain in the facility, and initiates a mental illness hold. The hold may not exceed twenty-four hours from the facility's receipt of the parent's written notice to terminate. The facility director, administrator, or psychiatrist shall immediately complete and submit a petition for immediate intervention under the provisions of § 27A-15-30 to the chair of the county mental illness board where the minor is located. For purposes of this section, the term, immediately, means the earliest possible time during normal waking hours. If a petition is not filed with the chair within twenty-four hours of the initiation of the hold, the minor shall be discharged. Upon informing a staff member of the inpatient psychiatric facility of the intention to terminate inpatient treatment, the facility shall promptly supply the parent with the required written form. If a § 27A-15-30 petition is completed for submission to the chair of the county board, the minor's admission shall continue pending the decision of the chair under § 27A-15-34.
SDCL 27A-15-12