Did Miranda v. Arizona rely on precedents created by the US Supreme Court?

Answer 1

Yes. The Warren Court had previously ruled, in Escobedo v. Illinois, 378 US 478 (1964), when a police investigation is no longer a general inquiry about an unsolved crime, but focuses on a specific suspect, a defendant cannot be denied his constitutional right to assistance of counsel.

The Escobedo decision, in combination with Gideon v. Wainwright, (1963) and Mapp v. Ohio, (1961) had established a "fundamentals of fairness" standard designed to protect the constitutional rights of the accused. In Escobedo, the Court held the defendant had the right to counsel as soon as he or she was identified as a suspect in a criminal investigation. The Miranda ruling lowered the threshold for determining when an individual could invoke constitutional protection using the "right to leave" test, which includes any time the person no longer had the freedom to voluntarily remove himself from police custody.

In a narrow 5-4 vote, the Court ruled to reverse Miranda's conviction on the basis that he had not been correctly informed of his constitutional rights. The typed waiver at the bottom of the statement was held to be insufficient to constitute a valid waiver of rights. Failure to ensure the suspect understood his constitutional rights was a violation of the 14th Amendment Due Process Clause.

The case citation is Miranda v. Arizona,384 US 436 (1966)