In a twisted bit of logic that may be impenetrable to those of you who didn’t read law when you were getting your education, the Supreme Court of the USA has issued a ruling:
If you want to invoke your right to remain silent, you have to say so.
The guy-who-turned-out-to-be-a-murderer in question was being questioned by police as a murder suspect. They asked him about the murder weapon and he didn’t answer, so they moved on. His SILENCE when he was under no obligation to speak, and had been speaking, was used against him in court. He hadn’t been “properly” mirandized yet, had not been arrested, and did not claim to be silent to prevent incriminating himself. That, plus he was answering the rest of the questions asked by investigators, leads to the following logic from SCOTUS: If you want your silence not to be held as evidence against you, you MUST SAY that you are exercising your right not to speak.
You have the right not to give potentially-incriminating testimony against yourself. If, after this ruling, you ever find yourself speaking to the Police, be certain to tell them right at the beginning: “I understand that I have a right to remain silent. If I refuse to answer your questions, it is an exercise of my right not to say things that may tend to incriminate me.”
From the linked article:
“It has long been settled that the privilege ‘generally is not self-executing’ and that a witness who desires its protection ‘must claim it,” according to the lead opinion written by Justice Samuel Alito and joined by Chief Justice John Roberts and Justice Anthony Kennedy. “Although ‘no ritualistic formula is necessary in order to invoke the privilege’ … a witness does not do so by simply standing mute,” Alito added.