You've seen it time after time on primetime television police shows—cops slapping the cuffs on a "perp" and reading him his rights: "You have the right to remain silent. Anything you say can and will be used against you in a court of law." And so on. Believe it or not, this ubiquitous arrest scene presents a rare instance in which Hollywood stays true (for the most part) to the laws of criminal procedure.
Indeed, the (in)famous case of Miranda v. Arizona requires that law enforcement officers advise arrested suspects of certain rights, including the option of saying nothing. (384 U.S. 436 (1966).) Miranda, which derived from the Fifth Amendment privilege against self-incrimination, also triggered the practice of officers telling arrestees that:
This article focuses on the privilege against self-incrimination for suspects who are out of custody. To read about the prosecution using the silence of someone who's under arrest, see Miranda and Post-Arrest Silence.
Officers must provide Miranda warnings whenever they interrogate someone who is in custody. "Interrogation" includes not only express questioning but also any words or actions that police officers should know are reasonably likely to elicit an incriminating response. Being "in custody" describes a situation in which a reasonable person in the suspect's shoes would not feel free to leave.
The corollary of Miranda warnings is that the prosecution cannot use a suspect's silence as evidence of guilt in a court of law—otherwise the warnings would be meaningless. But, the law doesn't require interrogating police officers to "Mirandize" someone who isn't technically "in custody." As a result, police officers routinely question suspects after carefully letting them know that they are not under arrest and are free to leave—that way, officers don't have to provide Miranda warnings. Even in that situation, though, suspects' silence was sacrosanct: Prosecutors couldn't use it against them at a later trial. That is, until somewhat recently.
In a closely contested 2013 decision, the U.S. Supreme Court held that prosecutors can, under appropriate circumstances, point to an out-of-custody suspect's silence in response to police questioning as evidence of guilt. (Salinas v. Texas, 133 S. Ct. 2174 (2013).)
According to the Court, the prosecution can comment on the silence of a suspect who:
The only way to prevent the government from introducing evidence of the suspect's silence at trial is to explicitly invoke (assert) the right to say nothing. In other words, without being warned by the police or advised by a lawyer, and without even the benefit of the familiar Miranda warnings (which might trigger an "I want to invoke my right to be silent!"), the interviewee must apparently say words to the effect of, "I invoke my privilege against self-incrimination."
(To read about an earlier Supreme Court decision on silence before arrest, see Can a prosecutor use pre-arrest, pre-questioning silence to "impeach" a defendant?)
In the case that led to this new rule, a police officer who was investigating a murder asked the suspect (and eventual defendant), who was not then in custody, a series of questions over the course of an hour. The officer did not Mirandize the suspect. The suspect answered the questions but hesitated when the officer asked whether a ballistics test would prove that the shell casings at the crime scene matched the suspect's gun. He fidgeted for a bit and didn't answer the question; the officer then moved on to additional questions that the suspect answered. Prosecutors then charged the suspect with murder. At trial, they argued that his reaction to the officer's shell-casing question suggested his guilt. The Court ruled that this argument by the prosecutors was proper—the defendant had not clearly indicated that he intended to assert his Fifth Amendment right when asked about the shell casings.
The 2013 Supreme Court decision raises weighty questions, such as whether it's reasonable to place the onus of asserting constitutional rights on everyday people—most of whom have never cracked the spine of a criminal procedure or constitutional law book. The more practical question is what, exactly, an out-of-custody person must say to inquisitive police officers in order to effectively claim the right to silence. Courts have indicated that they should make clear that they are invoking their Fifth Amendment privilege against self-incrimination. That way their subsequent silence cannot be mentioned at trial.
(The ACLU advises people about what to do and say when stopped by law enforcement, noting that in some states, if the police ask you to identify yourself, you must give your name.)
The U.S. Supreme Court has the final say on the meaning of the federal Constitution, but state courts can interpret their own constitutions to provide greater individual freedom. The law on silence and self-incrimination may vary from one state to the next. That variation is one of many reasons it's critical to have legal representation when facing criminal charges.