Fourteenth Amendment, Section 1:
All persons born or naturalized in the United States, and subject to the jurisdiction thereof, are citizens of the United States and of the State wherein they reside. No State shall make or enforce any law which shall abridge the privileges or immunities of citizens of the United States; nor shall any State deprive any person of life, liberty, or property, without due process of law; nor deny to any person within its jurisdiction the equal protection of the laws.
In Afroyim v. Rusk, 1 a divided Court extended the force of this first sentence beyond prior holdings, ruling that it withdrew from the government of the United States the power to expatriate United States citizens against their will for any reason.
[T]he Amendment can most reasonably be read as defining a citizenship which a citizen keeps unless he voluntarily relinquishes it. Once acquired, this Fourteenth Amendment citizenship was not to be shifted, canceled, or diluted at the will of the Federal Government, the States, or any other government unit. 2 In a subsequent decision, however, the Court held that persons who were statutorily naturalized by being born abroad of at least one American parent could not claim the protection of the first sentence of section 1 and that Congress could therefore impose a reasonable and non-arbitrary condition subsequent upon their continued retention of United States citizenship. 3 Between these two decisions is a tension that should call forth further litigation efforts to explore the meaning of the citizenship sentence of the Fourteenth Amendment.