Harris v. New York (1971)
The Court said that Miranda did not mean that evidence barred from use during the prosecution's case could not be used for any purpose. They said the Miranda protection could not be "perverted into a license to use perjury by way of a defense, free from the risk of confrontation with prior inconsistent utterances."
Michigan v. Tucker (1974)
The Court ruled that the witness could testify. In this case they made a distinction between a violation of the Fifth Amendment right against self-incrimination and a mere violation of the Miranda rule. Since the defendant was warned about his right against self-incrimination, the Court allowed the witness to testify.
Oregon v. Elstad (1985)
The Court ruled that admissions made prior to Miranda warnings must be suppressed, but later statements, if made voluntarily, may be used in court. "[T]he mere fact that a suspect has made an unwarned admission does not warrant a presumption of compulsion," Justice O'Connor wrote.
Illinois v. Perkins (1990)
Justice Kennedy, writing for the majority, held that conversations between suspects and undercover officers are not held in a "police-dominated atmosphere" and therefore Miranda warnings are not necessary. No coercion was possible because there was no official interrogation.
New York v. Quarles (1984)
The Court said there is a "public safety" exception which applies in this case. The police officer acted to further public safety and therefore the statement made by the defendant telling of the location of the weapon) before his Miranda rights were read to him was admissible in court.