The most damaging evidence in a drunk driving case, as in most criminal cases, often comes from the defendant's own mouth: admissions. Although the statements may be spontaneous and thus not subject to suppression on Miranda grounds, they usually come in reply to a series of questions asked by the investigating officer. These questions tend to follow a rather routine format, and are generally geared to determining what and how much the suspect has had to drink; when and where he or she has been drinking; whether the defendant's memory or mental awareness has been impaired ("Where are you? What time is it?"); the possible presence of drugs or medication; and the absence of any illness or medical condition, to preclude later claims that they affected his or her symptoms or performance. In fact, these questions can be so predictable that many law enforcement agencies have formalized the interrogation in DUI cases by printing a list of questions in their arrest report forms.
The usual admissions issue in a drunk driving case involves the question of exactly when the officer should have given the Miranda advisements. The usual prosecution argument is that although the defendant was not free to leave, the questioning was part of a preliminary investigation, conducted before the individual had been placed in custody, and thus the advisements were not yet required. In fact, however, the officer will almost always have decided at a very early stage that the suspect was intoxicated. Long before the officer begins any questioning, he or she will probably have observed such symptoms as erratic driving, alcoholic breath, bloodshot eyes, thick and slurred speech, and staggering out of the car. Rather than being investigative in nature, the questioning is usually a means of gathering evidence with which to "nail the lid shut."
The focus, then, is on when the warnings should have been given to the defendant. This involves a legal issue and a factual one. The legal issue concerns what standards are to be applied: should warnings be given only when a suspect has, in fact, been arrested? When the suspect's freedom was significantly curtailed? When there existed probable cause to arrest? Are the Miranda standards different in DUI cases? The factual issue involves the question of what, in fact, happened: when was the defendant, in fact, arrested-or deprived of his or her freedom in a substantial way? When did the officer have probable cause to arrest? In resolving these issues, it must be kept in mind that this is a subject about which police officers are commonly very willing to commit perjury. The simple fact is that court-wise officers will rarely admit what they know to be true: that they have probable cause to arrest a suspect before they questioned the suspect.