Rising Blood Alcohol as a California DUI Defense

When alcohol enters your body, it absorbs into your bloodstream.  As it does this, your blood alcohol concentration (BAC) continues to rise until you have reached what is known as your "peak" absorption rate.

If you got arrested for California Vehicle Code 23152b VC, but provided a DUI blood or DUI breath sample before you reached your peak absorption rate, the results of your DUI chemical test were probably falsely high.  It is this type of scenario that lends itself to the "Rising Blood Alcohol" California DUI defense.

How alcohol absorption affects California DUI breath test results

Alcohol "absorption" is the passage of alcohol into the bloodstream.  On average, alcohol takes about 50 minutes to absorb into your system after you stop drinking, although it may take as long as three hours.1 The absorption process is affected by a variety of factors such as:2

  • whether you eat while you consume the alcohol,
  • whether you drink on an empty stomach,
  • what type of alcohol you drink,
  • how quickly/slowly you drink (referred to as your drinking pattern), and
  • your blood-to-breath partition ratio.3 (*Your blood-to-breath partition ratio is the relationship between the alcohol measured in your breath and the alcohol measured in your blood.)

As a result, if your absorption process isn't complete by the time you submit to a DUI blood test or a DUI breath test, your BAC is still rising (which is why this DUI defense is known as the "on the rise" defense).

Let's say, for example, that your DUI breath test...taken an hour or so after you drove...reveals a 0.10%.  Your California DUI defense attorney could argue that your BAC was still rising at the time of your test...which means that it is likely that your BAC could have been below a 0.08% at the time you drove.4

In order to be convicted of California Vehicle Code 23152b driving with a BAC of at least 0.08%, your BAC must be at that level at the time of driving

Although this fact seems obvious, it is often overlooked or brushed aside by officers, prosecutors, and sometimes even judges.  This is because it is convenient for the prosecution simply to assume that if you tested above the legal limit, you must have driven above the legal limit.

Science contradicts that logic.  As Michael Scafiddi, a top-notch San Bernardino DUI defense attorney explains5, "If, for example, you had 'one for the road', your BAC was likely still rising at the time of your DUI blood test or DUI breath test.  As a result, although your BAC may have been above the legal limit at the time of your test, that doesn't mean it was necessarily above the legal limit at the time you drove."

Call us for help.

If you or loved one is charged with a DUI and you are looking to hire an attorney for representation, we invite you to contact us at Shouse Law Group. We can provide a free consultation in office or by phone. We have local offices in Los Angeles, the San Fernando Valley, Pasadena, Long Beach, Orange County, Ventura, San Bernardino, Rancho Cucamonga, Riverside, San Diego, Sacramento, Oakland, San Francisco, San Jose and throughout California.

You may also find helpful information in our related articles on California Breath Testing, DUI Blood Testing, Vehicle Code 23152b Driving with a BAC of 0.08%, and California DUI Defenses.

Legal References:

1Lawrence Taylor "Drunk Driving Defense" 3d Edition, page 611, discussing the rising blood alcohol DUI defense.  ("In a recent study, researchers found that absorption continued for an average of 50 minutes after cessation of drinking...The mentioned 50-minute absorption period is, of course, an average; the actual period can vary from a � hour to as long as 3 hours and this can be extended by recent ingestion of food...")

2See same at 610.  The absorption process is affected by factors such as food ingestion, pattern of drinking, and individual blood/breath partition ratio.

3People v. McNeal (2009), 46 Cal.4th 1183, 1188.  ("Whereas a blood test directly measures the subject's blood-alcohol level, a breath sample must be converted to derive a blood-alcohol percentage. The conversion factor, known as a "partition ratio," reflects the relationship between alcohol measured in a person's breath and alcohol in the blood.")

4See "Drunk Driving Defense" endnote 1 above at 611.  ("Thus, in most cases the arrestee who had 'one for the road' is still absorbing alcohol at the time of the test -- and even an accurate test result will be higher than the actual blood-alcohol concentration at the time of driving.")  Contact us for more information about how we effectively present the "one for the road" defense.

5San Bernardino DUI defense attorney Michael Scafiddi is a former DUI enforcement officer who now uses that inside knowledge to help defend clients accused of DUI in California.  He practices DUI defense primarily in the San Bernardino and Riverside Counties, and makes appearances at the Murrieta Southwest Justice Center and in Banning, Fontana, Joshua Tree, Barstow, and Victorville. Mr. Scafiddi has testified as an expert witness in DUI trials, and frequently uses "Rising Blood Alcohol" as a DUI defense.

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