SDCL § 25-3-2: Unsound mind as ground--Party bringing action--Time of action.

A marriage may be annulled by an action in the circuit court to obtain a decree of nullity if either party was of unsound mind at the time of the marriage, unless such party, after coming to reason, freely cohabitated with the other as husband or wife. An action to obtain a decree of nullity of marriage for causes mentioned in this section must be commenced by the party injured, or relative or guardian of the party of unsound mind, at any time before the death of either party.