Blood Alcohol Concentration (BAC) in California

Per California Vehicle Code 23152 (a), a person can be charged and convicted of driving under the influence (DUI) if the driver has a blood alcohol concentration of 0.08% or higher (or lower in some cases) while operating a vehicle. While BAC isn’t the “be-all-end-all” of DUI evidence in every case, if you are pulled over and your BAC is more than 0.08%, you will be arrested and face some type of punishment. Generally, the higher your BAC, the harsher the penalties you will face. Likewise, if you cause harm to others or property damage while DUI, you will face harsher penalties as well. Essentially, BAC is a huge piece of evidence in a DUI case.

Basic BAC Facts
  1. The California Driver handbook states that licensed drivers operating a vehicle cannot have a BAC of 0.08% or higher. That said, you can be convicted of a DUI with a BAC of less than 0.08%.
  2. It is illegal for drivers licensed to operate commercial vehicles (Class A and B licensees) to operate any vehicle (not just commercial vehicles) with a BAC of 0.04% or higher.
  3. It is illegal for drivers under 21 to operate any vehicle with a BAC of 0.01% or higher. A driver with a BAC of 0.01 percent or higher is subject to California’s zero tolerance program meant to reduce underage DUI.
Does my BAC need to be 0.08% or higher to get a DUI?

The short answer is no. The police officer who pulled you over has the discretion to determine whether your mental faculties were impaired to the point in which you were unable to safely operate your vehicle. In this case, the officer would have had to observe you exhibiting behaviors consistent with a person who was impaired by drugs or alcohol. Similarly, in the event you were impaired because you used marijuana, your BAC would be 0.0%. But if the officer saw you swerving, driving too slow, or if you had been involved in a traffic accident, you could be at risk of facing DUI charges.

How would an officer determine my mental faculties were impaired if my BAC was below 0.08%?

Police officers are trained in detecting the signs of driver impairment. First, an officer will observe your driving. If your driving is erratic, including swerving, not keeping up with the flow of traffic, you were involved in an accident (whether you were at fault or not), failure to signal when turning, quickly turning, driving on the wrong side of the road, or really any behavior that would be probably cause for an officer to make a traffic stop.

Second, police officers use field sobriety tests (FSTs). An officer will pull you over and ask you to step out of the vehicle. It should be noted that you are not required to submit to FSTs (See notes below regarding refusing FSTs). FSTs are used to collect evidence against you in the event you are actually driving while impaired.

There are 3 tests law enforcement uses to collect evidence against drivers suspected of driving under the influence:

  1. The walk and turn test
    1. The police officer will explain the actions he or she wants the suspected driver to perform. Usually this includes walking, one foot in front of the other, heel to toe, for a determined length (a parking spot line is frequently used). Then the officer instructs the driver to turn 180 degrees and walk the length of the line again.
    2. Officers are looking for the driver to exhibit a lack of balance, an inability to follow directions, and/or any other indication that the driver’s cognitive ability might be inhibited.
  2. The one-leg stand test
    1. Again, the police officer will explain the actions he or she wants the suspected driver to perform. Fort his test the officer may instruct the driver to stand on one foot and recite the alphabet backwards, or count down from 100-0 until the officer tells the driver to stop.
    2. Officers are looking for discoordination, inability to balance on one foot, inability to complete both tasks without error, or an inability to focus on talking while standing on one foot.
  3. The horizontal gaze nystagmus (HGN) test
    1. The officer will instruct the driver to remove any eyeglasses or hard contacts.
    2. Without lateral head movement, the officer will instruct the driver to follow his or her finger only using the driver’s eyes, and only return the eyes to center once the officer instructs the driver to do so.
    3. Once the officer’s fingers reaches the far right or left limit as instructed by NHTSA, the officer looks for the eyes to start “jerking” or twitching as the eye muscles strain to keep the eyes in place.

While FSTs are subjective with respect to how evidence is collected by officers, there are scientific facts that backup the frequency with which FSTs, when properly administered, identify a driver with a BAC above a certain level. When the driver does not have a BAC above the legal limit, FSTs are used to collect evidence that will lead to a conviction of an impaired driver.

If you refuse to perform FSTs, be prepared to either perform a Breathalyzer test, or give a blood sample at the police station. If you refuse FSTs and BAC tests, your license can be suspended for 1 year due to implied consent laws.

DUIs can negatively effect many aspects of your life, including housing, employment, and your financial future. If you have been arrested for DUI, you have 10 days from your arrest to contact the DMV and apply for a restricted license. The Johnson Criminal Law Group has experienced DUI lawyers available to take your call 24 hours a day, 7 days a week. Call us now to get started on your DUI case.

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