Underage DUI under Vehicle Code 23140 applies to drivers under 21 with a blood-alcohol concentration of 0.05 percent or more, a lower threshold than the standard adult limit. I am Joel Brand, and here is what the statute covers, how it differs from the other underage and adult DUI laws, and how I defend it.
The text of the law
Vehicle Code 23140. (a) It is unlawful for a person under the age of 21 years who has 0.05 percent or more, by weight, of alcohol in his or her blood to drive a vehicle. (b) 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 0.05 percent or more, by weight, of alcohol in his or her blood. (c) Notwithstanding any provision of law to the contrary, upon a finding that a person has violated this section, the clerk of the court shall prepare within 10 days after the finding and immediately forward to the department an abstract of the record of the court in which the finding is made. That abstract shall be a public record and available for public inspection in the same manner as other records reported under Section 1803.
Where it sits among the underage laws
California has a layered set of rules for drivers under 21, and it helps to see how they fit together. The strictest is the zero-tolerance law, Vehicle Code 23136, a civil DMV provision triggered at just 0.01 percent that costs a young driver the license. Section 23140 is the next step up: it is an infraction, not a civil matter, triggered at 0.05 percent. Above that sit the standard criminal DUI statutes, Vehicle Code 23152(a) and 23152(b), which apply to a driver of any age at 0.08 percent and carry the full misdemeanor consequences. A young driver can face more than one of these at once for the same stop.
What kind of offense this is
Importantly, a violation of 23140 is an infraction, not a misdemeanor. It does not carry jail time. The consequences are a fine, a one-year license suspension for a first offense, and, for drivers 18 or older, a requirement to complete an alcohol education program. That is a meaningful set of penalties, especially the license suspension for a young person who depends on driving, but it is categorically less severe than a criminal DUI conviction. Understanding which statute you are actually charged under is the first step, because the stakes and the strategy differ sharply.
The 0.05 percent threshold and why the chemistry matters
Because the line is drawn at 0.05 percent, the accuracy of the blood-alcohol measurement is central. At a level that low, the margin of error in breath testing, the timing of the test relative to driving, and the possibility of rising alcohol all matter even more than in a standard 0.08 case. A breath result near 0.05 is well within the range where instrument variability, mouth alcohol, and absorption-phase issues can move a reading across the legal line. I scrutinize the testing closely, because here a small measurement error is the difference between a violation and none at all.
Challenging the stop and the testing
The same defenses that apply to any DUI apply here, often with more force given the low threshold. First, was the traffic stop lawful? If the officer lacked a valid reason to pull the driver over, a motion to suppress under Penal Code 1538.5 can exclude everything that followed. Second, was the chemical testing reliable, properly administered, and correctly timed? And third, do the field sobriety observations actually support the charge, or are they the ordinary nervousness of a young driver stopped by police? Each of these is a genuine line of defense.
The DMV consequence runs separately
As with every California DUI, there are two separate proceedings: the court case on the 23140 charge and the DMV's administrative action against the license. The DMV process has its own deadlines and its own hearing, and it moves independently of the court. For a young driver, the license suspension is often the most painful consequence, so addressing the DMV side promptly, including requesting a hearing within the deadline, is essential. I handle both tracks together so the license is defended, not just the court charge.
Why a careful defense matters for a young person
It is tempting to treat an infraction as something to just pay and move past, but for someone under 21 the consequences reach further than the fine. A license suspension disrupts school, work, and daily life, and an alcohol-related entry on a young driving record can raise insurance costs for years. The 0.05 threshold also means these cases are genuinely winnable, because the chemistry sits so close to the line. Mounting a real defense, rather than simply conceding, is frequently worthwhile.
When higher charges are also filed
If the driver's level was at or above 0.08, the prosecution may file the standard criminal DUI counts under 23152 alongside or instead of 23140. In that situation the full weight of a misdemeanor DUI defense applies, and the strategy shifts accordingly. Part of my early review is figuring out exactly what has been charged and where the measured level falls, because that determines whether we are fighting an infraction, a misdemeanor, or both.
How it fits the larger defense
An underage 23140 charge is defended with the same core tools as any DUI: attacking the lawfulness of the stop, the reliability of the chemical testing, and the field evidence. It connects directly to the zero-tolerance law and the standard 0.08 BAC statute. See my top DUI defenses and the defenses guide for the full approach.
Under 21 and charged with a DUI? Let's talk.
These cases are more defensible than they look, and protecting a young driver's license and record is exactly what I do. Use the free case analysis on this page, or call me directly at (888) 271-6644. I answer my own phone, 24/7.