Suppose the police pull you over on suspicion of drunk driving. It comes out later that your BAC test result showed something like 0.06. “Wonderful,” you may think. “That means police have to drop the charges. My BAC has to be 0.08 for an arrest to stick.”
Not so fast, though. The reality is that in Arizona, you can receive DUI charges no matter your BAC level. There does have to be probable cause to suspect that alcohol has impaired your functioning to drive, but that impairment can be quite slight.
Evidence in addition to BAC
Alleged actions on your part, such as stumbling when you exit your car, weaving while driving, speeding or being unable to balance well during field sobriety tests, can all serve as evidence that you should not have been driving. That can lead to DUI charges sticking and to you receiving a conviction. Of course, many people have reasons that their behavior could have seemed suspicious. A disability such as autism, for example, can make it difficult for drivers to maintain eye contact with police officers, and hearing impairment can cause speech that seems slurred.
Assuming the police officer pulled you over for a reason such as believing that you were driving recklessly or speeding, there is usually some type of evidence that a prosecutor can present in addition to BAC test results. That said, there may not have been enough reasonable suspicion to pull you over in the first place.
Why bother having a BAC number?
Since arrest is acceptable with, say, a 0.057 BAC, why bother with having a 0.08 BAC number at all? The answer is that 0.08 serves as a general guideline for when people are too impaired to drive safely, but there is only so much that a generalization can do. For example, a small woman who rarely drinks might reach 0.08 far faster than a large man who drinks regularly. Even if her BAC is under 0.08, the fact that she rarely drinks alcohol could mean that she is driving dangerously. Thus, police officers can use their judgment to charge someone with DUI despite the person having a BAC under 0.08.