The case in which the Supreme Court ruled that confessions cannot be introduced as evidence unless they were offered after police advised the suspect of his or her legal rights was Miranda v. Arizona.
In 1963, Ernesto Arturo Miranda was arrested for kidnapping and sexual abuse, which he confessed without any warning of his constitutional right to remain silent, or his right to have a lawyer present at the time of declaring. At the trial, the prosecutor offered only his confession as evidence and Miranda was convicted.
The Supreme Court ruled that Miranda had been intimidated during his interrogation and that he had not understood his right not to incriminate himself or his right to be assisted by a lawyer. On these grounds, the Court reversed the previous ruling. Miranda was later sentenced in another trial, with witnesses testifying against him and other evidence presented. He served 11 years in prison.