Cannabis is legal for adults in California. Driving while impaired by it is not. A lot of people learn that distinction the hard way, after getting pulled over and arrested even though what they did was perfectly legal to buy and use. If that's where you are right now, you're not alone, and you're not without options.
Marijuana DUI cases are some of the shakiest cases the prosecution brings, because the science of measuring cannabis impairment is genuinely unsettled. That cuts both ways. It means these cases can be scary and confusing, but it also means there's real room to fight them.
Overview
California prosecutes driving under the influence of marijuana under Vehicle Code 23152(f), the same statute that covers other drugs. It's unlawful to drive while impaired by cannabis, whether you smoked it, ate it, or used it any other way, and whether or not you have a medical recommendation or bought it legally at a dispensary. Legal to possess and legal to consume does not mean legal to drive impaired.
Here's what makes marijuana DUI cases different from alcohol cases, and even from many other drug cases. There is no per se limit for THC in California. With alcohol, a 0.08 BAC lets the prosecution charge you on the number alone. With cannabis, there's no magic number of nanograms that automatically means you were too impaired to drive. The prosecution has to prove that marijuana actually impaired your ability to drive as a sober, cautious person would.
That's a real hurdle for the prosecution, because THC behaves very differently from alcohol in the body. Alcohol leaves the system fairly predictably. THC does not. It can stay detectable in blood for hours or even days after the effects have worn off, and for regular users it can linger far longer. So a blood test showing THC does not reliably tell anyone whether you were impaired at the moment you were driving. A frequent user could test positive while completely sober. That disconnect is central to how these cases are defended.
To make their case, police lean on observations rather than a clean number. That usually means field sobriety tests, the officer's observations of things like odor, red eyes, or behavior, and often a Drug Recognition Expert evaluation, plus a blood test. Each of these has weaknesses. And as with every DUI, two separate cases run at once. The criminal case is in San Diego County Superior Court, and the DMV handles your license through the Administrative Per Se process with a 10-day window to request a hearing after arrest. Our DMV hearings page explains that side.
Joe's Approach
Joe Crudo approaches a marijuana DUI knowing the prosecution's science is far from airtight. When you call Crudo Law, you deal directly with Joe. There's no handoff to someone who has never spoken with you. That direct attorney access means the person building your defense understands the specifics of your stop and your case.
Joe's starting point is the gap between what a THC blood test shows and what it actually proves. A positive test tells you cannabis is present. It does not tell you when you used it, how much, or whether you were impaired while driving. For a regular or medical cannabis user, that gap is enormous. Joe uses it. The prosecution's burden is to prove actual impairment, and the tools they use to do it, from roadside tests to DRE evaluations, are all open to challenge.
Joe also looks closely at the human explanations for what an officer read as impairment. Red eyes, nervousness, and slower responses can come from allergies, fatigue, anxiety, or simply the stress of being stopped by police. The smell of cannabis in a car, or the fact that someone consumed hours earlier, doesn't establish that they were impaired at the wheel. Sorting the real evidence from the assumptions is a big part of the work.
Because these cases rest so heavily on subjective observation, Joe treats the details as decisive. Exactly what the officer saw, how the field sobriety tests were run, whether the DRE followed protocol, and how the blood was collected and tested all matter. Cases from central San Diego are typically heard at the Central Division downtown, while North County cases generally go to Vista, though the assigned court can vary by charge and filing. You can read more about Joe's philosophy on the about page.
Defense Strategies
Every case is different and no result is guaranteed, but marijuana DUI cases have specific weak points. Here are some of the angles Joe evaluates.
THC presence does not equal impairment. This is the core of most marijuana DUI defenses. Because THC can stay in the body long after any effect on driving has ended, a positive blood test does not establish impairment at the time of driving. For regular and medical users, THC can be detectable well past any impairing effect. Making the prosecution prove actual impairment, not just presence, is often the whole battle.
No per se limit. Unlike alcohol's 0.08 standard, California has no set THC threshold that proves impairment. That means the prosecution can't fall back on a number and must rely on observations that are open to interpretation and challenge.
Field sobriety tests. These tests were built around alcohol and are hard even for sober people. Nerves, tiredness, injuries, footwear, uneven ground, and medical conditions all affect performance. Struggling on them is not proof of cannabis impairment.
Challenging the DRE evaluation. A Drug Recognition Expert evaluation is a structured protocol carried out by a human officer. Whether the officer was properly certified, whether each step was followed, and whether the conclusions actually hold up can all be questioned. It's an opinion, not a lab measurement.
Innocent explanations. Allergies, fatigue, anxiety, contact lenses, and the ordinary stress of a police stop can produce the physical signs officers attribute to marijuana. Prior lawful use hours earlier is not evidence of impairment while driving.
Blood testing problems. Collection, storage, timing, and lab analysis all create room for error. Chain of custody and contamination issues can undermine a result, and a blood split motion may allow independent retesting. Our BAC defense page covers how testing gets challenged.
The stop. If police lacked a lawful reason to pull you over, the evidence that followed may be subject to a suppression motion.
Depending on the facts, one goal in some cases is a reduction to a lesser offense like a wet reckless, which carries lighter consequences than a DUI conviction. Whether that's possible depends on the evidence, your record, and the circumstances.
Potential Outcomes
Read this as a general picture rather than a prediction. A first-offense marijuana DUI in California is generally charged as a misdemeanor, with a penalty range similar to an alcohol DUI. That can include fines and fees, a court-ordered DUI or drug education program, informal probation that commonly runs 3 to 5 years, and possible county jail exposure up to 6 months for a first offense, though jail is not automatic for a first-time offender.
The license consequences work differently than in an alcohol case. The DMV's per se administrative suspension is tied to a 0.08 alcohol reading, so a pure marijuana DUI may not trigger that same automatic suspension. A conviction in court, however, can still lead to a license suspension. The exact interplay depends on your record and the facts, which is why getting advice about your specific situation is worth doing. If alcohol was also in the picture, the standard 10-day DMV rule likely applies, so don't assume the DMV side is irrelevant.
Priors change the math. A second or third marijuana DUI carries steeper penalties, and a case involving injury to another person falls under Vehicle Code 23153 and can be charged much more seriously, potentially as a felony depending on the circumstances.
Outside the courtroom, a marijuana DUI can affect employment, professional licensing, and insurance, and it goes on your record. In many cases a conviction can later be expunged after successful completion of probation, but the best strategy is to fight for a strong outcome up front rather than counting on cleanup down the road.