The U.S. Supreme Court says suspects have to be clear about their desires.
If you’re in the custody of the police and they’re questioning you, your Miranda rights automatically apply. Typically, the police must provide the Miranda warning, and you must waive it—rather than fail to assert it—for your statements to be admissible as evidence of guilt at your trial.
But the U.S. Supreme Court has held that officers can continue to question in-custody suspects until such suspects clearly and unequivocally invoke their Fifth Amendment rights. To stop the questioning, the suspect must unambiguously assert either the right to silence or the right to counsel. (But see Police Questioning After the Suspect Claims Miranda.)
For information on invoking these rights, see:
- Is post-arrest silence enough to stop police questioning? and
- Miranda: Claiming the Right to Counsel
You might also want to see What’s the best way to assert my right to remain silent if I am being questioned by the police?
Be mindful that states are free to provide more protections for criminal defendants than the federal Constitution does. To learn the exact law in your state and how it applies to your situation, talk to an experienced criminal defense lawyer.