Recognizing Defenses in DUI Cases

Laws against drunk driving have been reinforced over the past twenty years, both by creating new offenses and by increasing the penalties for existing offenses. The national campaign to “get tough on drunk drivers” has produced specialized training programs for both prosecutors and police officers. Chemical testing has become more sophisticated and is increasingly relied on in the prosecution of drunk or impaired driving cases. Juries, reflecting the national concern over drunk driving, have become much more inclined to return guilty verdicts than in past decades. Appellate courts and trial judges, from the Supreme Court down, have become generally unsympathetic to drunk drivers in their rulings and opinions.Not surprisingly, the defense of DUI-DWI cases has become increasingly difficult. Many of the defenses and strategies that worked in the 1970s are no longer effective. Defenses and techniques, both legal and scientific, that were unknown ten years ago must now be recognized and implemented if a defendant is to be adequately represented. Both the incredible body of recent case law and the scientific advances in chemical testing have rendered it difficult for the general practitioner to keep abreast of the defenses that may or should be raised on behalf of defendants in drunk or impaired driving cases.

Like other criminal case defenses, some defenses in DUI-DWI cases are obvious, while others must be sought out with a knowing eye. To enable defense counsel to ask the appropriate questions and take the appropriate investigative and procedural steps, it is important to have a working knowledge of the matters that may give rise to defenses in drunk driving cases. While attorneys who specialize in DUI and DWI cases are likely to possess such knowledge intuitively, those who handle only an occasional impaired driving case often do not. The Summary of DUI Driving Defenses is designed to assist defendants in anticipating and recognizing defenses in typical DUI-DWI cases.

Defenses in drunk driving cases may be substantive, procedural, or tactical, and they may appear in any phase or aspect of the case. Generally, however, meaningful defenses are most likely to be found in two areas of a typical DUI case: (1) in the events surrounding the stop and arrest of the defendant, and (2) in the chemical testing aspect of the case. Most violations of the defendant’s constitutional or statutory rights occur during the stop and arrest of the defendant, and the application of the exclusionary rule and the fruit of the poisonous tree doctrine to such violations can render this phase of the case productive of important defenses. The many opportunities for error, both foundational and discrediting, in the chemical testing process can render this phase of the case productive of several defenses, which, because of the importance of chemical test evidence in impaired driving cases, can play an important role in the outcome of a case.

It is, of course, impossible to list and summarize every conceivable defense that may arise in a DUI-DWI case. Therefore, the Summary of DUI Driving Defenses is general in nature and includes those defenses that are most likely to arise in a typical drunk or impaired driving case. This summary should be used as a guide. DUI-DWI cases should not be limited to the defenses appearing in the summary.