Most people are familiar with the first lines of the Miranda warning, "you have the right to remain silent. Anything you say or do can and will be held against you in a court of law." However, not everyone is aware of the specific constitutional rights embodied in the warning.
The Miranda warning originates from the 1966 Supreme Court case Miranda v. Arizona. In Miranda, the United States Supreme Court held that it was a violation of a person's 5th Amendment right against self-incrimination to be interrogated while in police custody without being warned of the right not to speak.
If police fail to inform a suspect of their Miranda right to remain silent and interrogate him while in custody, any confession or incriminating information stemming from the interrogation will not be admissible in court.
Miranda warnings are meant to counter-balance the inherently coercive and intimidating setting of a custodial interrogation. However, Miranda warnings are not always required. A suspect must only be informed of their 5th Amendment right if he or she is (1) interrogated by a known state agent (2) while in custody.
First, Miranda protections apply only to testimonial evidence. Testimonial evidence includes verbal, written or other non-verbal communication intended to convey thoughts or offered as proof of the truth of what is being stated. For example, if a person nods her head in response to a question, this is non-verbal testimonial evidence and therefore protected by Miranda. However, physical or real evidence is not protected by the 5th Amendment clause against self-incrimination. Physical evidence includes hair, skin, DNA, and handwriting samples. It also includes fingerprints and voice exemplars.
Second, the suspect must actually know that the person conducting the interrogation is a state agent for Miranda protections to apply. This requirement is usually easy to meet when an individual is questioned by a known police officer. However, there is no Miranda protection for statements gathered by a private person's interrogation, regardless of whether the suspect is in custody or not. Courts have also held that Miranda excludes interrogations by police informants or undercover police officers. The rationale behind this is that if the suspect does not know the other person is a state agent, there is no coercion.
It is also important to define both "interrogation" and "custody" for purposes of Miranda warnings. Under federal and New Mexico case law, "interrogation" for 5th Amendment purposes has a precise definition. For a situation to entail "interrogation" it must have been express questioning. The Supreme Court defined interrogation as "any words or actions... that the police should know are reasonably likely to elicit an incriminating response." For example, a volunteered or spontaneous statement is not the product of interrogation and will be admissible in court even if the individual was not provided with Miranda warnings.
Finally, "custody" also has a specific meaning under Miranda case law. Custody, for 5th Amendment purposes, means that the person was formally placed under arrest or that his or her freedom of movement was so restrained that it is correlated to formal arrest. A person does not have to be physically restrained by an officer; the words, "you are under arrest" are enough to satisfy this requirement.
When there is no formal arrest courts must analyze whether the person reasonably believed he or she was free to leave and terminate the interview. According to federal and New Mexico law, however, brief traffic stops (Terry stops) or short questioning by a police officer on the street does not rise to the level of "full custodial arrest" under Miranda. Further, a person is not considered to be in custody when he voluntarily goes to a police station for questioning, especially if the officer warns that he is not under arrest and free to leave at any time.
Once interrogation has begun, a suspect is also entitled to retain an attorney or have one appointed to them if they are indigent. Once a suspect invokes their right to an attorney, all interrogation from police must end at once until the attorney has been contacted.
There is an important public safety exception to Miranda warnings. Statements obtained while in a situation that involved heightened public danger are admissible in the absence of Miranda warnings. However, this is a limited exception that only applies in situations where (1) the officer reasonably believed that the information was necessary to protect life and property form a substantial threat and (2) the questioning was restricted to what was reasonably necessary to acquire the information.
Each case is unique and likewise requires individual analysis. If you are facing a situation where you believe your Miranda rights have been violated, you should discuss the facts and circumstances with an experienced criminal defense attorney.