A violation of your Miranda rights might result in the dismissal of evidence against you, and the dismissal or reduction of the DUI charges. In a situation when you have been placed in “custody” due to your detention or arrest, and the officer attempts to interrogate you while you are in custody, the officer must advise you of your Miranda rights prior to the interrogation. The officer does not have the obligation to advise you of your rights when questioning and asking you questions when you are not considered to be in custody. The Miranda warnings are designed to advise you of your right to remain silent and the right to have an attorney present during questioning.
Miranda rights issues often play a limited role in DUI cases. The remedy for having your Miranda rights violated is limited to the suppression of the verbal statements you made to the officer so that your statements cannot be used as evidence against you. However, key evidence in DUI cases often consists of things other than what you have told the police. Often, the most critical evidence against you will consist of alcohol test results, or other evidence of bad driving, poor performance on the Field Sobriety Tests (FSTs) or objective symptoms such as red watery eyes or inability to maintain your balance while standing or walking. A violation of your Miranda rights will not enable you to suppress this kind of non-testimonial evidence. Further, the officer will often start asking questions before making any detention or arrest. In most situations, individuals who are facing DUI investigation will provide information, including self-incriminating information, voluntarily before they are placed in custody. In such situations, there is no Miranda rights violation because the officer does not have the obligation to warn you of anything prior to placing you in custody.
A Miranda rights violation might be key to defending and dismissing your DUI case if and when you were placed in custody, the officer started to interrogate you without giving you the required Miranda warnings, and you made self-incriminating statements which constitute evidence which is necessary or crucial to the District Attorney's case. One such example would be a scenario where after your Miranda rights have been violated you have admitted to being the driver, the prosecution does not have any other evidence to show that you were the driver, and your attorney was successful in suppressing your statement. Suppression of evidence in this kind of case can mean the difference between dismissal and DUI conviction.