The Supreme Court ruled in Afroyim's favor in a 5–4 decision issued on May 29, 1967. The opinion of the Court—written by Associate Justice Hugo Black, and joined by Chief Justice Warren and Associate Justices William O. Douglas and Abe Fortas—as well as Associate Justice Brennan, who had been part of the majority in Perez—was grounded in the reasoning Warren had used nine years earlier in his Perez dissent.Dionisopoulos (1970–71), p. 249. "By the narrow margin of five to four the Court [in Afroyim] had repudiated the precedent of Perez, denied to Congress any power to expatriate an American and subscribed to a principle espoused by Warren in his dissenting opinion almost a decade earlier."Matteo (1997), p. 41. "Nine years after Perez, Chief Justice Warren's dissent in that case became the basis of the majority opinion in the subjesequent judicial milestone, Afroyim v. Rusk. The court's majority now held that "Congress has no power under the Constitution to divest a person of his United States citizenship absent his voluntary renunciation thereof." Specifically repudiating Perez, the majority of the justices rejected the claim that Congress had any power to revoke citizenshipMatteo (1997), p. 41. "Justice Black rejected the Perez holding that sovereignty carried with it the implied power of involuntary expatriation." and said that "no such power can be sustained as an implied attribute of sovereignty". Instead, quoting from the Citizenship Clause, Black wrote:
