It seems a week does not go by when I am asked if a DUI driver has to be given "Miranda" warnings. Although a lot of lawyers quickly say, "no" without much thought, like most things in life, it's not simple. Some of the most damaging evidence in a DUI case often comes from the driver's own mouth: admissions. Most of the time, the statements are "volunteered" or are spontaneous, both of which are not protected on Miranda grounds. Generally, Miranda requires that 1) the person be in custody, and 2) answering specific questions designed to incriminate the person. In a DUI setting, the motorist is asked a general set of questions: How much the person has had to drink; Where they have been drinking; When they stopped drinking; Any medical conditions which might effect performance on FST's (Field Sobriety Tests). In fact, these questions are so predictable that most law enforcement agencies have a printed list of questions for the officer to ask.
When I am asked this question, my response is: As in life, there are general rules and then there are exceptions. The average lawyer stops at the general rule. The good DUI lawyer looks for the exceptions. Although the general rule might be that Miranda does not apply in DUI arrests; the Supreme Court in Pennsylvania v Muniz, (1990) 496U.S. 582, held that most of the questions asked of an in-custody driver were routine and did not require Miranda warnings to be given. However, when the driver could not remember the date of his 6th birthday, the court found Miranda was required. The court stated, "Muniz was left with the choice of incriminating himself by admitting that he did not then know the date of his sixth birthday or answering untruthfully by reporting a date that he did not then believe to be accurate (an incorrect guess would be incriminating as well as untruthful)." The court also stated that Muniz's incriminating utterances during the FST's were "voluntary" in the sense that they were not elicited in response to specific questions. This means that if the officer asks a counting test or the ABC's, Miranda would be required!
So, the answer to the question whether Miranda warnings should have been given to the motorist involves a close look at the specific facts of the arrest. Was the motorist actually placed under arrest? or was the driver no longer free to leave? Is the officer asking "routine" booking type of questions? or is the officer asking specific questions designed to eliminate possible defenses or gain incriminating evidence? At what point is the preliminary investigation over and the officer's mind in made up that the driver is DUI, and now the questioning is a means to "nail the case shut"? So the fact that most cops and a lot of lawyers think Miranda never applies to a DUI arrest- is just plain wrong.