To be guilty of DWI, there are two different “theories” by which the prosecutors can prove you guilty. The first is by proving that you were impaired by alcohol while you were driving. The second is by proving that the alcohol content in your body was at a certain level within three hours of when you were driving. If the prosecution can prove to the judge or jury beyond a reasonable doubt that one of these two theories is true, you are guilty of DWI.
Impaired by alcohol: In a DWI trial, the jury will be instructed that the prosecution must prove that “as a result of drinking liquor the defendant was less able to the slightest degree, either mentally or physically, or both, to exercise the clear judgment and steady hand necessary to handle a vehicle with safety to the person and the public.” Here is some evidence that helps them prove this. First, if an officer sees you driving poorly, that is evidence that you were impaired while driving. Bad driving may include weaving in and out of a lane, running a stop sign or light, suddenly stopping, driving too slow, or too fast; generally, the prosecution can say that failing to follow the “rules of the road” is evidence of impairment.
Second, an officer may, after pulling you over, ask you various questions. In response, you might admit that you had been drinking. He might notice slurred speech and clumsy answers. He might smell alcohol on your breath or see your blood-shot, watery eyes. He could see an open container of an alcoholic beverage. This is all evidence the prosecution would want to admit to prove impairment by alcohol.
Finally, the officer may ask you to perform “standardized field sobriety tests.” There is interesting scientific research behind these tests with respect to what they show. But on an intuitive level, these tests ask you to perform various balancing, thinking, and dexterity tasks. You may be asked to stand on one leg and count. You may be asked to walk a certain number of steps there and back on a straight line. Whatever the science says, if the police officer records you stumbling, falling down, messing up the instructions, or making other clumsy errors, that is evidence of impairment too.
As a matter of common sense, we all have an idea of what effect alcohol has on a person and how to spot it. Correspondingly, these three types of evidence, while pretty typical in a DWI trial, can be supplemented in a number of ways. In analyzing whether this evidence in any given case can prove the prosecution’s theory, the devil is in the details, the strength of the evidence, and the existence of any defeating defenses to the contrary.
BAC at or above the limit: The other theory is considerably more technical and ultimately black and white. BAC is short for blood alcohol content—how much alcohol is there in your body? There are two ways the police are testing that level: through a sample of your breath or your blood. The most common way they test for it is through taking a breath sample from the Intoxilyzer 8000 machine, which they have here, for example, in downtown Albuquerque.
New Mexico law states that anyone who drives is deemed to have consented to giving a BAC test when he or she is arrested on a DWI charge. If, upon arrest, you refuse to give a BAC test, the State will charge you with Aggravated DWI, which has an enhanced and mandatory jail time punishment if convicted.
Upon taking the test within 3 hours of driving, if the score is .08 or above, you are by law guilty of DWI. If the score is .16 or higher, you are by law guilty of Aggravated DWI. If you are under 21 years old, you are guilty if the score is .02 or over, and if you are driving a commercial vehicle, you are guilty if the score is .04 or over.
Weight, drink strength, food eaten, metabolism, and other factors are determinative, but generally, 3-5 drinks within an hour can get a person to a .08 BAC.
If your score is at or just slightly above the limit, there may still be tactics and techniques a polished attorney can try to prevail, including challenging the reliability of the testing, noting the margin of error, or disputing the prosecution’s foundation for the test.