You may have heard that people under the age of twenty-one (21) face a lower threshold for being convicted of California DUI. This is correct. The laws that apply to underage (under-21) DUI in California are a bit different than those for people 21 and older.
The first thing to remember is that if you break the standard (adult) DUI laws in California, you will be charged with DUI even if you are under 21 (or under 18). You do this by driving "under the influence" under Vehicle Code 23152(a) VC, or by driving with a blood alcohol content (BAC) of 0.08% or higher under Vehicle Code 23152(b) VC.
But, if you are under 21, you have to worry about a few additional laws as well. These are:
Vehicle Code 23136 VC, California's "zero tolerance" law. California's so-called "zero tolerance" underage DUI law punishes drivers under 21 who drive with any detectable amount of alcohol in their system (i.e., with a BAC of 0.01% or higher).
VC 23136 is not actually a criminal offense, so it does not lead to jail time, criminal fines or a DUI on your record. But it WILL result in a one-year suspension of your driver's license if you do not contest the suspension.
Vehicle Code 23140 VC, California's underage DUI law. This special form of DUI applies only to drivers under 21. Underage drivers can be convicted under VC 23140 for driving with a BAC of 0.05% or above--considerably lower than the threshold for standard DUI.
Luckily, VC 23140 is an infraction. This means that it will not result in jail time. But it can lead to a fine, a one-year suspension of your driver's license and/or three or more months of mandatory DUI school.