It is possible to face impaired driving charges even if your blood alcohol concentration does not exceed the legal limit. That being said, police often use breath tests to check a person’s BAC because this provides evidence against that driver. Someone who has exceeded the BAC limit can be presumed to be impaired.
One thing that many drivers find themselves wondering, then, is how fast their BAC is going to drop after they stop drinking. Would someone who has spent the evening at the bar be safe to drive after waiting for an hour? How long would it take before they would pass that breath test?
The average rate of decline
Although there can be some differences from person to person, studies tend to find that the average rate of decline for blood alcohol concentration is just 0.015 per hour.
This is relatively slow. It would take four hours to get back to zero from a BAC of 0.06, for example, which is already under the legal limit. Someone who was well over that limit could need a significant amount of time before they would be completely sober.
Can anything speed this up?
No, there is nothing that can meaningfully increase the rate. For instance, some people believe that you can drink a cup of coffee and it will cause your BAC to drop as you sober up. But the reality is that caffeine just makes you feel more awake, which can cause someone to feel sober—even though they still have an elevated BAC.
The only real way to get your BAC to go down is to let time pass as your body metabolizes the alcohol content.
If you are facing drunk driving charges, you may have questions about how BAC tests were conducted or if the police followed the proper procedures. It is very important to understand all of the legal defense options at your disposal.