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What Does "Rising BAC" Mean in a DUI Case?

Recently we discussed the mouth alcohol defense, Breathalyzera defense that’s used when trace amounts of alcohol in the mouth throw off a breath test. But breath tests aren’t the only kind of chemical test that police use in DUI cases, and some factors can fool all of them across the board. One of the most serious is “rising BAC.”

What is Rising BAC?

Rising alcohol refers to the fact that your blood alcohol concentration (BAC) continues to go up long after you had your last drink. BAC is the truest measure of how intoxicated you are, because it measures the actual amount alcohol in your bloodstream, not just how many drinks you consumed or when. Different individuals can feel very different in terms of inebriation after having, say, three drinks each. But two individuals with the same BAC will experience a nearly identical level of impairment.
“Impairment” here is the key word. The law says you cannot drive if you are impaired by alcohol, and the threshold is set at .08% BAC. If you’re pulled over and have your BAC tested immediately, then — if done properly — the result should be a very accurate measure of how impaired you are.

But what if the test isn’t done until hours later?

Common sense would tell us that you would be less drunk, i.e., you’d have a lower BAC. But that’s not the case. Instead, BAC continues to rise for hours after you stop drinking, because it takes time for your body to absorb all of the alcohol. The result: you could be within the legal limit while driving, get arrested for DUI, and be over the limit by the time they finally test you.

Rising BAC as a DUI Defense

Judges don’t always like the rising BAC defense. This is partly because it’s hard to prove, and partly because law enforcement can’t always issue a proper blood or breath test immediately. They may have to take other calls before getting you back to the station, or may need time to get the equipment ready before they test you. In some cases, the jail facility is simply busy.

However, the science is clear that delaying a blood or breath test can cause an unfairly high BAC result. And there are plenty of cases where rising BAC has been enough to give a jury reasonable doubt and lead to an acquittal, or simply get a favorable offer from a prosecutor. Generally, the defense works best if your tested BAC was close to the legal limit, and if there was a clear, documented delay of an hour or more before you were tested.

Could rising BAC have affected your case? If so, you may have a strong defense against your DUI charge. Let the experienced DUI attorneys of The Wilson Law Firm help you with that defense.

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