If a police officer questions a suspect who's in custody without giving the suspect the Miranda warnings, nothing the suspect says can be used against the suspect at trial to prove their guilt. By excluding such evidence, the rule seeks to prevent the police from abusing their power to obtain a confession. The Miranda warning informs suspects of their constitutional rights to remain silent and consult with an attorney. But, as with most legal rules, exceptions exist.
This article will discuss when a suspect's statements can be used against them despite being obtained in violation of Miranda.
In the years since the Miranda case was decided (1966), several exceptions to the above rule have emerged from the courts. These exceptions assume that the only reason the statement is inadmissible in court is due to the Miranda violation (and not other possible forms of police misconduct, such as physical coercion).
If a defendant gives testimony at trial that conflicts with a statement made to the police, the prosecutor can offer a statement elicited in violation of Miranda to impeach (attack) the defendant's credibility. (Harris v. New York, 401 U.S. 222 (1971).) Say the defendant testifies at trial that he has never sold drugs in his life. But during a police interrogation, he admitted to selling drugs in the past. The police obtained the pretrial statement in violation of Miranda. The prosecutor can't admit the statement to prove the defendant's crime but can use it for impeachment purposes to show the defendant is giving two different versions of the story (and one must be a lie).
Similarly, rules in many jurisdictions allow prosecutors to offer statements obtained in violation of Miranda against defendants in sentencing hearings. (U.S. v. Nichols, 438 F.3d 437 (4th Cir. 2006).) For example, assume that in an improperly obtained statement a defendant admits to the police that he was armed with a weapon when he committed a crime. The defendant's confession may not be admissible at trial to prove the defendant's guilt, but the prosecutor may offer it as evidence during sentencing to try to obtain a harsher sentence.
Here are some other common exceptions to the Miranda rule:
Public safety exception. In dangerous situations, the "public safety" exception allows police officers to question suspects about weapons without giving a Miranda warning. If the interrogation leads the police to a weapon, it can be used against the suspect at trial. (N.Y. v. Quarles, 467 U.S. 649 (1984); see The Public Safety Exception to Miranda for more detail.)
Discovery of physical evidence. Dangerous situation or not, any physical evidence (such as a threatening note or the loot from a robbery) that the police learn about through questioning that violates Miranda can generally be used against a suspect in court. (U.S. v. Patane, 543 U.S.630 (2004); see If the Police Find Evidence Because of a Miranda Violation, Is the Evidence Inadmissible?)
Discovery of witness. If a statement taken in violation of Miranda leads the police to another witness, that witness can testify against a suspect at trial. (Michigan v. Tucker, 417 U.S. 433 (1974).)
"Inevitable discovery" rule. If the police would have eventually found tangible evidence on their own, the evidence can be used against a suspect at trial even if the police actually found out about it during questioning that violated Miranda.
These exceptions arguably give the police incentive to violate the Miranda rule. Suspects sometimes mistakenly think that what they say—or evidence found because of what they say—won't be admissible.
If you've been arrested or are facing questioning by police, it's generally best to consult with a criminal defense lawyer before answering questions. A lawyer can help protect your constitutional rights and navigate the complex criminal justice system.