In Edwards v. Arizona (1980), the U.S. Supreme Court ruled in favor of Edwards, establishing that once a suspect has invoked their right to counsel during custodial interrogation, law enforcement cannot initiate further questioning without the presence of an attorney. The case arose when Robert Allen Edwards Jr., who was arrested and charged with robbery, burglary and first-degree murder in Arizona, requested but did not receive legal representation during police interrogations after his initial arraignment. Despite initially invoking his right to remain silent and requesting counsel, he later made incriminating statements without an attorney present following continued police-initiated questioning over several days. The court held that this violated his Fifth Amendment rights against self-incrimination as defined by Miranda v. Arizona (1966). This decision reinforced suspects' protections under Miranda warnings by clarifying that if they request legal representation at any point during custodial interrogation process - even after initially waiving those rights - all subsequent questioning must cease until an attorney is present.

In the dissenting opinion for Edwards v. Arizona, Justice Powell argued that the majority's decision to prohibit further police-initiated interrogation after a suspect has requested counsel was an unnecessary extension of Miranda rights. He contended that this ruling could potentially hinder law enforcement’s ability to investigate crimes effectively and efficiently. The justice believed that as long as suspects were informed about their rights and voluntarily chose to speak with authorities without legal representation present, such interactions should be permissible under the Constitution. Furthermore, he expressed concern over how this new rule would be applied in practice given its potential ambiguity regarding when a suspect had sufficiently invoked his right to counsel so as to trigger these additional protections.