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California Driving Under the Influence - Basic Elements of the Case

California Vehicle Code SS 23152 and 23153 make it unlawful for any person to be operating a motor vehicle while under the influence of alcohol and/or drugs. In order for a person to be not only charged, but convicted of a Driving under the influence , or DUI, Prosecution must prove certain elements beyond a reasonable doubt.

What Must Prosecution Prove to Establish a Case for DUI?

Prosecution must prove that there was probable cause to arrest the person driving, that the person had in fact been driving, and they had a Blood Alcohol Level (BAC) that demonstrated intoxication.

Probable Cause

Officers may not stop a person unless they have a reason to do so. Many times the reason is a simple and obvious one such as weaving in and out of lanes, speeding, or running a stop sign or red light. Other times the reason is more subtle such as a broken tail light or expired license tags. Either way, the officer has a right to pull over the person if there is a valid reason, or probable cause, to do so. Once the person has been stopped, the officer may ask the driver to take a field sobriety test if there are signs that the driver may be intoxicated; slurred speech, red eyes, odor of alcohol, etc.


In addition to driving, there must be proof that the person was driving at the time they were intoxicated. The easiest way to prove this element is for the officer to directly observe the person driving and then pull them over and administer a field sobriety test that indicates intoxication. It is a little more difficult when the person is pulled over on the side of the highway or in a parking lot. In those cases where direct observation does not meet the driving element, the prosecution will use circumstantial evidence to arrive at the conclusion that the person was driving. Key facts will play a crucial role in proving this element in those situations: where were the keys to the car, where was the intoxicated person sitting in the car, were there other people, how warm was the engine?

Blood Alcohol Level Indicating Intoxication

Last, but not least, the person must be intoxicated. Although case law has determined that a .08% of alcohol indicates that a person is intoxicated, the actual Vehicle Codes do not mention any specific percentage. This means that although the accepted BAC is .08%, a person who has a lower BAC may still be charged with a DUI.