How can statements obtained in violation of Miranda be used?

Statements obtained in violation of Miranda rights can be used to impeach the defendant's own trial testimony. This means that if a defendant chooses to testify in their own defense and makes statements that contradict earlier statements made during an interrogation without proper Miranda warnings, the prosecution can use those prior statements to challenge the credibility of the defendant’s trial testimony.

The rationale behind this is rooted in the idea that while the initial failure to provide Miranda warnings renders the statements inadmissible as proof of guilt, they can still be relevant to assess the truthfulness of the defendant’s assertions on the stand. This allows the jury to consider the consistency of the defendant's statements and the potential motivations behind them, thus impacting the overall reliability of the testimony.

The other choices reflect misunderstandings of the implications of a Miranda violation. For example, using such statements as evidence of guilt during trial is not permissible because they are considered involuntary due to the lack of proper advisement. Similarly, using these statements solely for plea negotiations or asserting that they cannot be used at all do not accurately reflect the limits and allowances made by courts regarding the use of unwarned statements in the judicial process.