How can a confession obtained in violation of Miranda be used during trial?

A confession obtained in violation of Miranda rights is generally inadmissible in the prosecution's case-in-chief to establish guilt. However, if a defendant takes the stand at trial and testifies, the prosecution can use that confession to impeach the defendant's credibility if they provide testimony that contradicts the confession. This means that if a defendant admits to committing certain actions or makes statements during their testimony that are inconsistent with their prior confession, the prosecution can introduce the confession to highlight this inconsistency, thereby undermining the defendant's testimony and credibility.

This use of the confession is permissible under the rationale that allowing the jury to see the entire picture, including contradictions in the defendant's statements, is critical in assessing the reliability of the defendant's claims. Essentially, the confession serves a different purpose in this context—aiming to challenge the truthfulness of the defendant's testimony rather than directly establishing guilt. This distinction is important in understanding the limitations placed on confessions obtained in violation of Miranda rights while still acknowledging their potential relevance in the trial context if the defendant chooses to testify.