Vance v. Terrazas

Terrazas (plaintiff), a U.S. citizen born to a Mexican citizen, obtained a Mexican nationality certificate while a student in Mexico by swearing allegiance to Mexico and expressly renouncing his U.S. citizenship; the State Department issued a certificate of loss of nationality, and Terrazas sued for a declaration he remained a U.S. citizen. The trial court found the government proved by a preponderance of the evidence that Terrazas voluntarily relinquished citizenship, but the court of appeals reversed, holding the Constitution required a clear-and-convincing evidence standard that Congress couldn't lower; the Supreme Court granted certiorari.