Note: This is an educational course, not legal advice.
The Fifth Amendment says no person "shall be compelled in any criminal case to be a witness against himself." Police questioning in a closed room can pressure people to speak. In 1966 the Court created a rule to protect the privilege during questioning. It applies in state cases through incorporation (Malloy v. Hogan, 1964) and works alongside the exclusionary rule.
Why it works
Miranda applies only to custodial interrogation: both parts must be present. Custody means a formal arrest or restraint like one; a routine traffic stop ordinarily is not custody. Interrogation means express questioning or its functional equivalent, words or actions police should know are reasonably likely to draw an incriminating response (Rhode Island v. Innis, 1980). Volunteered statements are not covered. There are limits. In New York v. Quarles (1984) the Court allowed a question about where a gun was hidden in a store before warnings, under a public safety exception. A suspect who wants to stop must say so clearly (Berghuis v. Thompkins, 2010). And in Dickerson v. United States (2000), 7 to 2, the Court held that Miranda is a constitutional rule that Congress could not overrule by a 1968 statute making voluntariness the only test.
Key idea
Before custodial interrogation, police must give the Miranda warnings (silence; statements used in court; a lawyer; one appointed if needed). Both custody and interrogation are required. Dickerson (2000): Miranda is a constitutional rule Congress cannot overrule by statute.
Worked example: A street conversation
An officer walking a beat asks a man on the sidewalk, who is free to leave, whether he saw what happened at a store. The man says he did it. Miranda violation?
- There is questioning, but no custody: the man was free to leave and not under arrest.
- Miranda applies only to custodial interrogation.
Answer: No; the statement is admissible.
Worked example: A blurted statement
After an arrest, and before any questions, a suspect in the back of the patrol car says, "I knew I should not have taken the money." Admissible?
- There is custody, but no interrogation: the officers asked nothing and did nothing designed to draw a statement.
- Volunteered statements are not covered by Miranda.
Answer: Yes; it was volunteered.
Common mistake
Thinking Miranda applies whenever police speak with someone. It applies to custodial interrogation: both custody and questioning are required. Another slip: thinking a Miranda violation ends the case. Only the statements (and in some cases what they lead to) are excluded; other evidence remains.