No unauthorized act can be made valid, retroactively, to the prejudice of third persons, without their consent.
S.D. Codified Laws § 59-2-6
Ratification not to work injury to third persons
Source: CivC 1877, § 1352; CL 1887, § 3975; RCivC 1903, § 1671; RC 1919, § 1253; SDC 1939, § 3.0107.
Official source: South Dakota Legislature. Reproduced from public-domain South Dakota statutes; confirm against the official source for the current text. Not legal advice.