If you're stopped and accused of drunk driving, you have to defend yourself immediately. Being charged with this crime doesn't mean you are convicted, but it can be the start of a long battle to keep a conviction off your record and to keep your license and avoid penalties.
If you decide to have a defense in place, you don't have many options. However, you do have a few you can try. First, you can show why you had no choice but to drive even though you were intoxicated. For instance, if you were at home drinking and your child suffered an injury, then you may have felt you had no choice but to drive and take your child to the hospital.
Duress is another defense against a drunk driving charge. Here's an example: If you're at home with someone who suddenly attacks you and you need to leave to escape harm, your only choice may be to get into your vehicle and to leave the scene. In that case, you could show that you drove in order to avoid serious injury or death.
Mistake of fact is another defense option. This defense is used when a person honestly doesn't believe that he or she is intoxicated. A good example of this is if you take a medication that has the potential to make you drowsy, but you've been off it for 24 hours. By any calculation, it should be out of your system, but if you're suddenly affected by it, it could make you feel drunk or intoxicated, causing a problem on the roads. Your defense can be that you didn't know or should not have been affected by the drug at that point.
Source: FindLaw, "Defenses to Drunk Driving," accessed Aug. 27, 2015