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The "B" Count

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California Vehicle Code 23152(b), also known as the “B” count, makes it unlawful for a person to drive a motor vehicle with a blood alcohol of .08 percent or more.

What must the prosecutor show in order to find me guilty of the “B” Count?

In order to prove the crime of driving with a .08 percent or more, the prosecutor must show:

  1. You drove a vehicle, and

  2. When you drove a vehicle, you blood alcohol content was .08% or more.

Element 1: You drove a vehicle

In most cases the prosecution will be able to prove that you drove a vehicle because the arresting officer will have seen you driving the vehicle or will have pulled you over during a traffic stop. However, this is not required. The prosecution can use circumstantial evidence to prove that you were driving a vehicle. This may be witness statements, your own statements, or the officer's observations.

For Example:


Say an officer arrives on scene to an accident, two people are claimed to have been in the car. Both are intoxicated. One individual is 5’3 and the other is 6’4. Both claim that they were not driving the vehicle at the time of the accident. However, the officer looks around and notices that the driver seat is pushed forward up to the steering wheel and the mirrors are all set to a person of a smaller size. This is circumstantial evidence that the shorter person was the one driving the vehicle.

Element 2:  Your BAC was at or above .08%

While the “A” count will rely on both the subjective clues seen by an officer and the legal presumption afforded by the chemical test, the “B” count will rely almost entirely on scientific evidence and the opinions of a criminalist.


What will the criminalist testify to?

After arrest for a DUI, you will be provided with an admonishment that you are required to take a chemical test, whether it is blood or breath.  The results of that test will then be used to supply the basis of the criminalist opinion. The criminalist will use the results of this test to perform a calculation, known as retrograde extrapolation.

Retrograde Extrapolation

Retrograde extrapolation is a method to calculate a person’s BAC at the time of driving, based upon the results of a chemical test taken at a further time.

After a person consumes alcohol, the alcohol will be absorbed into the blood stream between 15 minutes to 1 hour.  The rate of absorption is debatable, but scientist agree that the rate of absorption is dependent in part on the contents of the person’s stomach.  After the person stops consuming alcohol they will reach a point known as “peak absorption”.  From that point, the person’s BAC will begin to fall as the body works to eliminate the alcohol from the blood stream.

The rate at which the fall occurs is often of debate among criminalist and toxicologist.  The established range is that the body eliminated between .015 to .020 per hour.  However, these rates are often disputed, and most medical and scientific journals will not cite them because of how much they vary. Most criminalist will use the .015 elimination rate, but the rates can be as low as .08 and as high as .35 per hour.

Using the elimination rate, and making a couple of assumptions, the criminalist will then “count backwards” to determine what the driver’s BAC was at the time of driving.

For Example:

A driver crashes his car at 8:25 pm.  When the police arrive on scene at 8:55 pm, they detect the odor of alcohol and begin a DUI investigation.  At 9:15 pm, the police administer a PAS test to the driver.  At 10:25 pm, the driver’s blood is drawn.  The results of the driver’s blood test comes back at .21 BAC.

Using this timeline, with a .21 BAC, the criminalist will count backwards, adding the elimination rate to each hour from the time of driving to the time the test was taken.  Using the .015 elimination rate, which is considered to be in favor of the defendant because it adds less, the criminalist will add .030 to the driver’s BAC.  Therefore, the criminalist will testify that at the time the driver crashed his car, the driver’s BAC was .24.

Now in order to make this calculation, the criminalist will be required to make three assumptions.  1) That the driver was in the elimination phase when they were driving. 2) That the driver had not consumed any alcohol around the time that the blood test and 3) that the driver did not have a rising BAC at the time the test was given.

Then based upon the results of this calculation, the prosecutor will argue what your BAC was at the time you were driving.

Legal Presumption

“If the People have proved beyond a reasonable doubt that a sample of the defendant’s blood or breath was taken within three hours of the defendant’s driving and that a chemical analysis of the sample showed a blood alcohol level of .08 percent or more, you may, but are not required to, conclude that the defendant’s blood alcohol level was .08 percent or more at the time of the alleged offense.”

Once the prosecution has called the criminalist to testify to the retrograde extrapolation calculation, then the prosecution will argue that based upon the results of that test, and through the legal presumption, that the jury can find you guilty.

Defenses to “B” Count

The most common defense to the “B” count is the rising defense.  The rising defense is used to show that at the time of the chemical test, you had not achieved peak absorption, and based upon this, at the time of your driving your BAC was not above a .08.

For Example: 

A person having a bad day takes two shots at a local bar and instantly leaves.  While driving, they are pulled over after only ten minutes from the time they left the bar. The officer smells the alcohol and places the driver under arrest.  The driver then submits to a blood test which results in a BAC of .09.  The prosecution will argue that the driver’s BAC at the time of driving would be approximately .10%.  However, through examination of the criminalist, the defense shows that if the driver’s BAC was rising, the driver’s BAC at the time of the driving was .05%.

Other defenses can include the attacking of the reliability of the chemical test or the method for testing the blood results.  In the case of a blood test, laboratories are held to high standards regarding the method and processing of blood however, they are prone to human error.  In the case of a breath test, the machines are maintained by humans and rely on proper calibration in order to prove reliable results.

Penalties for “B” Count

If you are convicted of a first DUI you can expect to face summary probation, up to six months in county jail, and fines between $390-$1,000.  The court will also order you to attend a DUI course that lasts between 3 to 9 months.  At the judge’s discretion, the court may order you to install an ignition interlock device.

For more information on Penalties, please visit our DUI Center

Dedicated DUI Attorney

Kevin Ballard is a dedicated DUI attorney based in Fairfield who understands how to effectively defend those charged with DUIs. Kevin is one of the few attorneys who is both a former prosecutor and trained as a police officer. As such, Kevin knows first hand how DUIs are handled from the initial traffic stop through prosecution and appeal. Let the Law Office of Kevin L. Ballard help you today defend your rights and protect your liberty.

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