California Vehicle Code § 23136
Blood Alcohol Concentration of .01 or greater; implied consent to testing; failure to submit to fo complete testing

1. Notwithstanding Sections 23152 and 23153, it is unlawful for a person under the age of 21 years who has a blood-alcohol concentration of 0.01 percent or greater, as measured by a preliminary alcohol screening test or other chemical test, to drive a vehicle. However, this section shall not be a bar to prosecution under Section 23152 or 23153 or any other provision of law.
2. A person shall be found to be in violation of subdivision (a) if the person was, at the time of driving, under the age of 21 years, and the trier of fact finds that the person had consumed an alcoholic beverage and was driving a vehicle with a blood-alcohol concentration of 0.01 percent or greater, as measured by a preliminary alcohol screening test or other chemical test.
3. 1. Any person under the age of 21 years who drives a motor vehicle is deemed to have given his or her consent to a preliminary alcohol screening test or other chemical test for the purpose of determining the presence of alcohol in the person, if lawfully detained for an alleged violation of subdivision (a).
   2. The testing shall be incidental to a lawful detention and administered at the direction of a peace officer having reasonable cause to believe the person was driving a motor vehicle in violation of subdivision (a).
   3. The person shall be told that his or her failure to submit to, or the failure to complete, a preliminary alcohol screening test or other chemical test as requested will result in the suspension or revocation of the person's privilege to operate a motor vehicle for a period of one year to three years, as provided in Section 13353.1.

California Vehicle Code§ 23140
Persons under 21 years of age; blood alcohol concentration of .05 or more

1. It is unlawful for a person under the age of 21 years who has .05 percent or more, by weight, of alcohol in his or her blood to drive a vehicle.
2. A person may be found to be in violation of subdivision (a) if the person was, at the time of driving, under the age of 21 years and under the influence of, or affected by, an alcoholic beverage regardless of whether a chemical test was made to determine that person's blood alcohol concentration and if the trier of fact finds that the person had consumed an alcoholic beverage and was driving a vehicle while having a concentration of .05 percent or more, by weight, of alcohol in his or her blood.