479 U.S. 157 (1986)
One-Sentence Takeaway: Coercive police activity is a necessary predicate to the finding that a confession is not “voluntary” within the meaning of the Due Process Clause of the Fourteenth Amendment.
Summary: A psychotic man approached police and declared that he had committed a murder and wanted to talk about it. After the man twice was advised of his Miranda rights, he told his story, offering many details about a murder. Ultimately, the state courts suppressed his confession on the ground that the man’s psychosis precluded him from making free and rational choices. In the Colorado Supreme Court’s opinion, such circumstances rendered the suspect’s confession involuntary, even though the police did nothing coercive.
The Supreme Court of the United States reversed. Specifically, the Court declared that “[w]e hold that coercive police activity is a necessary predicate to the finding that a confession is not ‘voluntary’ within the meaning of the Due Process Clause of the Fourteenth Amendment.” 479 U.S. at 167.