Decided the same day as Trop, the case of Perez v. Brownell upheld another provision of the 1940 Nationality Act, requiring expatriation for voting in a foreign election, which, according to the court, fell within Congress’s power to regulate foreign affairs. In another wartime case, Mendoza-Martinez (decided in 1963), the court struck down a provision that expatriated native-born or naturalized citizens who left or remained outside the country in time of war.65 There, the court invalidated what it deemed to be a penal sanction (denationalization) imposed without criminal process. Just a few years later, the court would revisit the question of Congress’s power to involuntarily denationalize American citizens for any reason, reversing its Perez decision. In Afroyim v. Rusk (1967), a naturalized American who voted in an election in Israel challenged the constitutionality of his subsequent expatriation under § 401(e). Afroyim drew on legislative history of the post-Civil War amendments and Civil Rights Act of 1866 to conclude that Congress had no power to involuntarily denationalize Americans: Citizenship in this Nation is a part of a cooperative affair. Its citizenry is the country, and the country is its citizenry. The very nature of our free government makes it completely incongruous to have a rule of law under which a group of citizens temporarily in office can deprive another group of citizens of their citizenship. We hold that the Fourteenth Amendment was designed to, and does, protect every citizen of this Nation against a congressional forcible destruction of his citizenship, whatever his creed, color, or race. Our holding does no more than to give to this citizen that which is his own, a constitutional right to remain a citizen in a free country unless he voluntarily relinquishes that citizenship.66 The Supreme Court decided Trop, Mendoza-Martinez, and Afroyim during the civil rights era. For the civil rights movement, “the fight for black freedom and equality [was] a fight to carry out America’s unfulfilled national ideals, which were embodied in the Constitution.”67 During this period, white nationalism receded from wide embrace by the American public and political class, and cases of denaturalization also became exceedingly rare. More recent developments related to the availability, exercise, and loss of American citizenship are explored in more depth later in this report. Vestiges of the Past: On the Security of Dual Nationality Although there are millions of dual or multi-nationals with United States citizenship, the United States does not officially recognize dual citizenship as an immigration status.68 According to the U.S. State Department, “U.S. law does not mention dual nationality…”69 At the same time, the State Department advises that, “U.S. law does not . . . require a person to choose one citizenship or another.”70 Yet the Oath of Allegiance that an individual takes in order to naturalize declares that the person “will renounce and abjure all allegiance and fidelity to any foreign prince, potentate, state, or sovereignty, of whom or which I have heretofore been a subject or citizen.”71 26 UNMAKING AMERICANS