In Frazier v. Cupp, 1968, the U.S Supreme Court ruled on the admissibility of a confession obtained by police during an interrogation where they had lied to the suspect about his cousin's confession. Jerry Rawls and Martin Frazier were arrested for murder in Oregon. During separate interrogations, detectives falsely told Frazier that Rawls confessed and implicated him in the crime. This led to Frazier confessing as well but later he sought to suppress this confession claiming it was coerced due to psychological pressure from law enforcement officers' deceptive tactics. The court held that while such deception is relevant when considering whether a defendant’s statements are voluntary or not, it does not automatically make them involuntary or exclude them from evidence at trial. The totality of circumstances must be considered including details like length of detention before questioning, delay in arraignment etc., which did not indicate coercion here according to majority opinion written by Justice Marshall Harlan II. Therefore, despite acknowledging some level of trickery used by police during interrogation process; SCOTUS upheld lower courts’ decisions allowing use of these confessions as evidence against defendants.

In the dissenting opinion for Frazier v. Cupp, Justice Douglas argued that the police had violated Frazier's constitutional rights by not informing him of his right to remain silent or have an attorney present during questioning. He believed that this failure rendered any subsequent confession involuntary and therefore inadmissible as evidence. Furthermore, he disagreed with the majority's view that a suspect must explicitly request legal counsel; instead, he contended that it was law enforcement’s responsibility to ensure suspects were aware of their rights before proceeding with interrogation. In addition, Douglas criticized the majority for ignoring what he saw as coercive tactics used by police officers during interrogations - including deception - which further undermined voluntariness of confessions obtained under such circumstances.