Judicial Proceedings and Custodial Interrogation
Generally, defendants are entitled to counsel from the time of their arraignment until the beginning of their trial. This is because the defendant's need for consultation, investigation, and preparation are critically important for a fair trial. The courts have gradually expanded this idea to the point that there is a legal concept of "a critical stage in a criminal proceeding" that indicates when a defendant must be represented by counsel.
Defendants who have been taken into custody and have invoked their Sixth Amendment right to counsel with respect to the offense for which they are being prosecuted may not later waive that right. However, defendants may waive their right under Miranda not to be questioned about unrelated and uncharged offenses.
What happens if the police violate the right to counsel? The remedy for violation of the Sixth Amendment rule is that any statements obtained from defendants under these circumstances will be excluded from the evidence at trial. There is one important exception to the Sixth Amendment exclusionary rule: evidence obtained from defendants held in custody that violates the Sixth Amendment may be used for the sole purpose of impeaching the defendants' testimony at trial.