Mistake of foreign laws is a mistake of fact.
S.D. Codified Laws § 53-4-11
Mistake of foreign law--Mistake of fact
Source: CivC 1877, § 890; CL 1887, § 3514; RCivC 1903, § 1208; RC 1919, § 823; SDC 1939, § 10.0314.
Official source: South Dakota Legislature. Reproduced from public-domain South Dakota statutes; confirm against the official source for the current text. Not legal advice.