S.D. Codified Laws § 23-24A-34
This agreement shall be liberally construed so as to effectuate its purposes. The provisions of this agreement shall be severable and if any phrase, clause, sentence, or provision of this agreement is declared to be contrary to the constitution of any party state or of the United States or the applicability thereof to any government, agency, person, or circumstance is held invalid, the validity of the remainder of this agreement and the applicability thereof to any government, agency, person, or circumstance shall not be affected thereby. If this agreement shall be held contrary to the constitution of any state party hereto, the agreement shall remain in full force and effect as to the remaining states and in full force and effect as to the state affected as to all severable matters.
SDCL 23-24A-34