San Diego BAC Defense Attorney

The whole DUI case against you often comes down to a single number. The officer says your blood alcohol content was 0.10, or 0.14, or 0.08, and suddenly that number feels like a done deal. It isn't. That number came from a machine or a lab, run by people, following procedures that can and do go wrong. A BAC result is evidence, and like any evidence, it can be challenged, weakened, and sometimes thrown out entirely.

Crudo Law defends drivers throughout San Diego who are facing DUI charges built on chemical test results. Attorney Joseph C. Crudo digs into the science and the procedure behind your BAC number, because that's where a lot of these cases get won.

Overview

BAC stands for blood alcohol content, the percentage of alcohol in your bloodstream. In California, the legal limits are set by statute. For most adult drivers, 0.08% or higher is over the limit under Vehicle Code 23152(b). For commercial drivers the limit drops to 0.04%, and for drivers under 21 the zero-tolerance rule sets it at just 0.01%.

Here's something a lot of people don't realize. In a California DUI case you're usually facing two separate charges at once. Vehicle Code 23152(a) covers driving under the influence, meaning your ability to drive was actually impaired. Vehicle Code 23152(b) is the "per se" charge, which says that driving with a BAC of 0.08% or more is illegal regardless of whether you seemed impaired. That per se charge is why the BAC number carries so much weight. Knock it down and the prosecution loses one of its two main theories.

Your BAC is measured one of two ways. A breath test estimates the alcohol in your blood based on the alcohol in your breath, using a conversion ratio that's assumed to be the same for everyone but really isn't. A blood test draws actual blood and analyzes it in a lab. Both methods have known sources of error, and California has strict regulations, often called Title 17, that dictate exactly how these tests must be performed. When the police or the lab don't follow the rules, the results become vulnerable.

It's also worth understanding that the BAC number shows up in two places: your criminal court case and your DMV Administrative Per Se hearing. Those run on separate tracks, and you have only 10 days after the arrest to request the DMV hearing that protects your license. Both proceedings can turn on the reliability of your BAC evidence, which is why challenging that number is so central to the defense. This work overlaps closely with our DMV hearing practice and the implied consent rules around chemical testing.

Joe's Approach

Joe doesn't take a BAC number at face value, and neither should you. When you bring him a case, one of the first things he does is request and comb through every scrap of documentation behind that result. For a breath test, that means the device's calibration and maintenance logs, its accuracy records, and the exact procedure the officer followed. For a blood test, it means the lab's analysis, the chain of custody, the qualifications of the analyst, and how the sample was stored.

Why so thorough? Because these numbers are only as good as the process that produced them, and the process is run by human beings under real-world conditions. Machines fall out of calibration. Officers skip the required observation period. Blood vials get stored wrong or mixed up. Any one of those problems can inflate a reading or make it flat-out unreliable.

Joe handles this personally. You're not going to get shuffled to someone who's never looked at your file. He reads the records himself, and when the science gets deep, he knows when and how to bring in independent experts, like forensic toxicologists, to expose the flaws in the state's evidence. He came up defending DUI cases in San Diego, so the technical fights over breath machines and blood draws are familiar territory, not something he's figuring out for the first time on your dime.

Just as important, Joe explains all of it to you in plain language. You don't need a chemistry degree to understand your own case. He'll walk you through what your number really means, where it's weak, and how that weakness translates into leverage, whether that's at the DMV, in negotiations, or at trial. You can read more about how he practices on the about page.

Defense Strategies

There are a lot of ways to attack a BAC result, and the right ones depend on how your test was done and what the records show. These are the challenges that come up most.

Rising blood alcohol. Alcohol takes time to absorb. Your BAC keeps climbing for a while after your last drink, which means the number the machine spits out at the station could be higher than what it actually was when you were behind the wheel. It's the "when you were driving" part that matters legally. If you were still absorbing alcohol, your BAC at the time of driving may have been under the limit even though the later test read over it.

Breath machine problems. Breathalyzers have to be properly calibrated and maintained, and the officer has to observe you for a set period, typically 15 minutes, to make sure you don't burp, belch, or regurgitate, which can throw the reading way off. Mouth alcohol, an empty stomach's worth of acid reflux, or residual alcohol from a recent drink or mouthwash can all spike a breath result. If the maintenance logs show problems or the officer cut corners on the observation, the reading is suspect.

Blood test errors. Blood cases have their own weak points. If the sample fermented because it was stored improperly or lacked the right preservative, the BAC can rise on its own inside the vial. If the chain of custody has gaps, or the lab's procedures don't hold up, the result can be challenged. Joe can also file a blood split motion to have the sample independently retested.

Title 17 violations. California regulations lay out exactly how chemical tests must be collected, handled, and analyzed. When law enforcement or the lab breaks those rules, it gives Joe a concrete basis to question or exclude the result.

Medical and physiological factors. Certain conditions can produce a falsely high reading. Acid reflux and GERD can push stomach alcohol up into a breath sample. Diabetes and low-carb or keto diets can produce acetone and other compounds that some breath machines misread as alcohol. If any of this applies to you, tell Joe, because it can matter a lot.

The 0.08 isn't the whole case. Even when the BAC number holds up, Joe attacks the broader case, from whether the traffic stop was legal to whether the field sobriety tests were administered correctly. A DUI has many moving parts, and the number is only one of them.

Potential Outcomes

Nobody can promise you a specific result, and BAC cases are no exception. What a strong challenge to your BAC evidence can do is change the whole shape of your case. Here's what that can look like, depending on the facts.

When a BAC result gets seriously undermined, the per se charge under Vehicle Code 23152(b) can weaken or fall away, and in some cases that leads to a dismissal or a favorable reduction. A common and valuable outcome is a reduction to a "wet reckless" under Vehicle Code 23103 per 23103.5, which carries lighter penalties and less long-term baggage than a full DUI conviction. That kind of reduction often becomes realistic precisely because the BAC evidence had real problems.

A successful challenge can also help you at the DMV. The Administrative Per Se suspension hinges in part on a BAC of 0.08% or more. If Joe can show the test was unreliable or the procedures broke down, that can help you keep your license, which for a lot of people matters as much as the criminal case.

Even when a conviction is the realistic outcome, chipping away at the BAC evidence gives Joe leverage in negotiations, which can mean reduced charges, lighter penalties, and staying out of jail. And if the case should be tried, a shaky BAC number is exactly the kind of reasonable doubt that a jury can hang onto.

The bottom line is that your BAC number is a starting point for the fight, not the end of the story.

Frequently asked

Common questions

Can I fight a DUI if my BAC was over 0.08?+

Yes. A BAC over 0.08 makes the case harder, but it's far from unbeatable. The number depends on a machine or a lab following the rules, and those rules get broken more often than people think. Joe challenges calibration, procedure, chain of custody, and the timing of your test through the rising blood alcohol defense. Even a reading over the limit can be undermined, and even when the number holds, the rest of the case, from the stop to the field sobriety tests, is still very much in play.

Are breathalyzer results always accurate?+

No. Breath machines are estimates, not perfect measurements, and they carry a built-in margin of error. They assume a standard breath-to-blood ratio that varies from person to person. They can be thrown off by mouth alcohol, burping, acid reflux, certain diets, and residual alcohol from mouthwash or a recent drink. They also have to be properly maintained and calibrated, and the officer has to follow the observation rules. When any of that goes wrong, the result can read high, and Joe knows where to look for it.

What is the rising blood alcohol defense?+

Alcohol doesn't hit your bloodstream all at once. After your last drink, your BAC keeps rising for a while as your body absorbs the alcohol. The law cares about your BAC at the moment you were driving, not later at the station. If you were still in the absorption phase when you were stopped, your BAC behind the wheel may have been lower than the number the test showed sometime afterward, possibly even under the legal limit. It's a real, science-based defense that fits certain fact patterns well.

Should I get a blood test instead of a breath test?+

There's no universal right answer, and it depends on the situation. One advantage of a blood test is that the sample is preserved, so it can be independently retested later through a blood split motion, which gives Joe a chance to verify or challenge the result. Breath samples aren't saved, so you can't recheck them. That said, blood tests have their own error sources, like fermentation and contamination. If you have a choice and a preference, that's worth discussing, but the more important thing is knowing your rights before you're ever in that position.

Can a medical condition cause a false high BAC reading?+

It can. Acid reflux and GERD can carry alcohol from your stomach up into a breath sample, spiking the reading. Diabetes and low-carb or keto diets can produce acetone and similar compounds that some breath machines mistake for alcohol. Certain other conditions can affect results too. If you have any of these, it's important to tell your lawyer, because a documented medical explanation can be a powerful part of challenging the number the machine reported.

If your DUI case hinges on a BAC number, don't assume that number is the last word. It came from a process that can fail, and it deserves a hard, informed challenge. Attorney Joseph C. Crudo offers a free and confidential consultation, and he'll take a real look at the evidence and tell you where it's vulnerable.

Call Crudo Law at (858) 622-7280 or reach out through our contact page. You'll speak directly with the attorney, and everything you share stays confidential.

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