Any person who's taken into police custody must be told that they have a Fifth Amendment right to not make self-incriminating statements and they have a right to an attorney. This rule is a result of the U.S. Supreme Court's decision in Miranda v. Arizona, which is why they're referred to as "Miranda rights."
In many ways, the Supreme Court's recognition of Miranda rights was one of the most significant advancements for the protection of individual rights during the criminal justice process. If suspects under custodial interrogation are not advised of their Miranda rights or if they invoke their rights, but the government persists in questioning them, then the court may prevent any subsequent statements from being used against them at trial.
To gain the full protection of Miranda rights, suspects must clearly invoke either the right to remain silent or the right to an attorney, and must not waive their Miranda rights. Suspects can waive their right to remain silent or their right to an attorney either expressly or implicitly. To expressly waive Miranda rights, the suspect would state (or sign something stating) that they waive the right to remain silent or the right to have an attorney present. Implied waiver means that the suspect behaves in a way that indicates a knowing and voluntary waiver of Miranda rights.
Before a suspect can waive their Miranda rights, they must first be informed of those rights, and must understand the rights as explained to them. From this point, the behavior of the suspect can constitute implied waiver of Miranda rights even if the suspect never explicitly states that they want to waive them.
Let's assume, for example, that after being informed of his right to silence and to an attorney, a suspect proceeds to make self-incriminating statements during interrogation. He may be found to have waived his right to silence by having been notified of his Miranda rights, understanding those rights, and then proceeding to make self-incriminating statements without an attorney present.
This implied waiver can also apply if the suspect is silent for a period of time before making the self-incriminating statements. This is best illustrated in a Supreme Court case where a suspect was read his Miranda rights but remained largely silent during a 3 hour interrogation. His only statement was "yes" when asked whether he prayed to God for forgiveness for the crime. The Supreme Court held that, although the suspect was silent after being read his rights and throughout most of the interrogation, this did not constitute an invocation of his right to silence or to counsel.
In other words, unless there's a clear invocation of Miranda rights in words or action, police can presume that a suspect is implicitly waiving those rights and can continue questioning until there is a clear invocation. So, even if a suspect thinks they're exercising their Miranda rights, their behavior could signal otherwise to law enforcement resulting in possible harm to them later at trial.
It's important to be aware that suspects aren't locked into any initial waivers, whether made expressly or implicitly. Instead, they always have the right to invoke their Miranda rights at a later time. If so, any statements obtained after the rights are invoked may be barred at trial.
If you're facing questioning by law enforcement, even if you may not be suspected of a crime, it's critical to know your rights and, more importantly, conduct that could constitute waiving Miranda rights. Fortunately, there are well-qualified criminal defense attorneys that can help. Reach out to an attorney in your area today to learn more.