Techt v. Hughes
Court of Appeals of New York
128 N.E. 185 (1920)
An American citizen died intestate in New York owning real property shortly after the United States went to war with Austria-Hungary. His daughter, Techt (plaintiff), had lost her U.S. citizenship by marrying an Austro-Hungarian citizen, and New York law allowed only citizens and "alien friends," not "alien enemies," to hold real property. Techt's sister, Hughes (defendant), argued Techt could not inherit because she was now an alien enemy, but Techt relied on a treaty between the United States and Austria allowing nationals of either country to take real property by descent. The lower court agreed Techt was not an alien friend, so her claim depended entirely on whether the treaty survived the outbreak of war.
Whether a treaty made between two nations during peacetime remains in force, and enforceable by individual citizens, after those nations go to war with each other.