As a result of the rule that even the courts of one State are not presumed to know the laws of other States and cannot take cognizance of them until legally proved, money paid by a citizen of one State under a mistake as to the law of a foreign State or of another of the United States is regarded as paid under a mistake of fact and therefore may be recovered:

Haven v. Foster, 1829, 9 Pick. (Mass.) 112; 19 Am. Dec. 353 : Mistake by residents of Massachusetts as to New York law of descent. Morton, J. (p. 130): "The parties knew, in {act, that the intestate died seised of estate situated in the State of New York. They must be presumed to know that the distribution of that estate must be governed by the laws of New York. But are they bound, on their peril, to know what the provisions of these laws are ? If the judicial tribunals are not presumed to know, why should private citizens be? If they are to be made known to the court by proof, like other facts, why should not ignorance of them by private individuals have the same effect upon their acts as ignorance of other facts?

Juris ignorantia est, cum jus nostram ignoramus, and does not extend to foreign laws or the statutes of other states."

Vinalv. Continental Const., etc., Co., 1889, 53 Hun (N. Y. Sup. Ct.) 247; 6 N. Y. Supp. 595: Mistake by nonresident as to validity of proceedings consolidating New York corporations. Learned, P. J. (p. 252): "Foreign laws (including laws of other states) are facts. The presumption that every one knows the laws of his own state is hard enough. He never is presumed to know the laws of all the other states in this country, and the laws of all the nations of the world."1

Presumably, however, relief would not be granted in case the law of the foreign State were the same as that of the plaintiff's domicile.