Motorists in Virginia who have been charged with driving while influenced by drugs or alcohol usually choose to avoid a trial by pleading guilty in return for a more lenient sentence. However, there are a number of options available if they choose to reject a plea agreement and mount a defense in court. Drivers who take this path can admit that they were intoxicated and mount what’s known as an affirmative defense, or they can question the evidence against them such as the results of toxicology tests or the observations of the police officers involved.
One of the most common affirmative defenses to DUI charges is involuntary intoxication. Motorists could mount this defense if they took drugs or consumed alcohol unknowingly. This strategy could also be taken when drivers consumed substances knowingly but were not aware of their intoxicating effects. Affirmative defenses can also be mounted by drivers who consumed intoxicating substances under duress or knowingly drove drunk because failing to do so would lead to an even greater harm.
Drunk driving defendants more commonly argue that police officers conducted a traffic stop without probable cause or administered breath tests improperly. Toxicology evidence could be challenged when maintenance records reveal that breath-testing equipment had not been adequately maintained or the samples used to conduct blood tests were mishandled. DUI charges can also be challenged on medical grounds when defendants suffer from any of the numerous conditions that have been known to influence toxicology tests.
When the evidence against their clients is compelling but not conclusive, experienced criminal defense attorneys may make these arguments at the negotiating table. Prosecutors work under great pressure and usually have heavy caseloads. Therefore, they may be willing to lower drunk driving penalties substantially to avoid having police reports or toxicology evidence challenged in court.