You get pulled over on a Friday night somewhere off the 5, the officer says he smells alcohol, and then he asks you to blow into a device. Your brain is running fast. Do you have to? What happens if you say no? Can you just refuse everything and make the whole thing harder to prove?
This is one of the most common questions I get, and the honest answer is that it depends entirely on which test the officer is talking about. California has two very different kinds of breath tests, and the rules for each are almost opposite. Get them confused and you can make a bad night much worse. So let me walk you through it the way I would if you called my office.
This is general information, not legal advice, and every stop is different. But if you understand the basics before you ever get pulled over, you will make far better decisions than most people do.
There Are Two Different Breath Tests, and That Is the Whole Ballgame
When people say "breathalyzer," they usually mean one machine. In reality there are two situations where an officer asks you to breathe into something during a DUI investigation, and the law treats them very differently.
The first is the roadside test, called a Preliminary Alcohol Screening test, or PAS. This is the handheld gadget the officer pulls out on the side of the road, usually before he has decided whether to arrest you. It is part of the officer's investigation, along with the field sobriety tests. Its job is to help the officer build probable cause.
The second is the evidentiary chemical test. This one happens after you have been arrested for DUI. It might be a larger breath machine back at the station or a mobile testing van, or it might be a blood draw. This is the test that produces the number the prosecutor uses in court.
The reason this distinction matters so much is that you generally have a right to decline the first one, but declining the second one triggers a separate set of penalties under California's implied consent law. If you want the deeper legal background on that, our page on implied consent breaks it down further.
The Roadside PAS Test: Usually Optional for Adults
Here is the part most people never learn until it is too late. If you are 21 or older and you are not currently on probation for a DUI, the roadside PAS test is generally optional. It is a field sobriety test that happens to be electronic. The officer is supposed to advise you that it is voluntary and that you can decline it. In practice, plenty of officers skip that part or say it so quickly you never catch it.
Why would you decline a voluntary roadside test? Because the PAS number can be used to help establish probable cause to arrest you, and these handheld units are not as reliable as the evidentiary machines. Mouth alcohol, recent burps, breath spray, certain medical conditions, and improper timing can all skew a roadside reading high. I have written more about how these machines go wrong in our article on breathalyzer errors and wrongful DUI arrests.
There are two big exceptions to the "PAS is optional" rule. If you are under 21, California's zero-tolerance law requires you to submit to a PAS test, and refusing carries its own license consequences. If you are on DUI probation, you are also required to submit. For everyone else, declining the roadside PAS is not the same thing as refusing a chemical test, and it does not by itself trigger the harsh refusal penalties.
I want to be clear about something. Declining the roadside PAS does not mean the officer cannot arrest you. If he already believes you are impaired based on driving, appearance, the smell of alcohol, and the field sobriety tests, he can arrest you anyway. And once you are arrested, everything changes.
The Chemical Test After Arrest: This Is Where Implied Consent Kicks In
When you got your California driver license, you agreed to something called implied consent. Under Vehicle Code section 23612, by driving on California roads you are considered to have consented to a chemical test of your blood or breath if you are lawfully arrested for DUI. This is the post-arrest test, not the roadside gadget.
Once you have been lawfully arrested, refusing this chemical test is a serious problem. It is not a clever loophole. The refusal itself becomes a penalty on top of whatever the DUI case does. And the evidence does not disappear the way people hope. In many situations, if you refuse, officers can seek a warrant and draw your blood anyway, so you can end up with both the chemical evidence and the refusal penalties.
The officer is required to read you an admonition explaining that refusing will result in a license suspension and can add jail time. If you refuse after hearing that warning, the state treats it as a knowing refusal.
The Real Consequences of a Chemical Test Refusal
This is the part people underestimate. A refusal is punished harder than simply failing the test in several ways.
Longer license suspension. For a first DUI where you take the test and fail, the DMV administrative suspension is typically around four months. Refuse the chemical test on a first offense and you are looking at a one-year suspension, and unlike a standard first-offense suspension, this refusal suspension generally does not allow a restricted license to get you to work and back during that period. That difference alone changes people's lives for a year.
It gets worse with priors. A refusal with a prior DUI or refusal on your record within the washout period can mean a two-year or three-year license revocation. The math stacks up quickly.
Added jail time and enhancements. A refusal allegation attached to a DUI conviction can add mandatory jail time and additional DUI school on top of the base penalties. The prosecutor treats the refusal as an aggravating factor.
It can be used as consciousness of guilt. Prosecutors are allowed to argue to a jury that you refused because you knew you were drunk. That is a powerful and unfair-feeling argument, but it is legal, and juries hear it.
So the strategy some people imagine, where refusing means "no number, no case," usually backfires. You often end up with a case built on the officer's observations, the driving pattern, the field sobriety tests, and the refusal itself, plus the longer suspension. Our page on refusing a breath test goes deeper into how these cases are charged and defended.
Two Cases, Two Clocks: The DMV and the Court
A DUI arrest that involves a refusal actually creates two separate proceedings, and people miss this constantly.
One is the criminal case in San Diego County Superior Court, where you face the DUI charge and any refusal enhancement.
The other is the administrative case with the DMV, which handles your license through the Administrative Per Se process. The DMV does not care whether you are convicted in court. It runs its own track, and the refusal allegation is decided there.
Here is the deadline that trips people up. You have only ten days from your arrest to request a DMV hearing. Miss it and the suspension takes effect automatically, and in a refusal case that can be the full year with no restricted license. Ten days goes fast when you are shaken up and not thinking about paperwork. I wrote a whole piece on this called the 10-day rule, and it is worth reading the moment you or someone you love gets arrested. You can also learn more about the hearing itself on our DMV hearings page.
Can a Refusal Case Be Fought? Often, Yes
A refusal allegation is not automatic just because the officer wrote "refused" in the report. The law has requirements, and when the state cuts corners, there is room to challenge the allegation. Some of the questions I look at in these cases:
Was the arrest lawful? Implied consent only applies after a lawful arrest. If the initial stop or the arrest was not supported by proper cause, the refusal allegation can fall apart with it.
Was the admonition actually given, and given correctly? Officers are required to warn you of the consequences of refusing. If that warning was garbled, incomplete, or never given, that matters.
Was it really a refusal? People with asthma, dental issues, anxiety, or certain injuries sometimes cannot produce a valid breath sample even when they are trying. A failure to complete the test is not always a legal refusal. Confusion caused by the officer's own conflicting instructions can also undercut a refusal claim.
Did the officer offer a choice where required? The rules about which tests must be offered and when have specifics that officers do not always follow.
None of this guarantees an outcome. Every case turns on its own facts, and I never promise results. But I look hard at whether the refusal allegation was properly built, because knocking it out removes the extra suspension and the extra jail exposure. This is the kind of detailed review I bring to every BAC and chemical test defense case that comes through my door.
So What Should You Actually Do?
I cannot tell you in a blog post to refuse or not refuse a chemical test, because the right move depends on your exact situation, your record, and what happened during the stop. What I can tell you is this. The roadside PAS test is generally optional for sober-minded adults over 21 who are not on DUI probation, and there is often little upside to blowing into it. The post-arrest chemical test is a different animal, and refusing it carries real, heavy, separate penalties under implied consent that frequently outweigh what people think they are avoiding.
Stay calm. Be polite. Do not argue or resist. And get a lawyer involved fast, because that ten-day DMV clock does not wait for you to feel ready.
If you have been arrested for a DUI in San Diego and there is a refusal allegation, do not sit on it. The window to protect your license is short, and the sooner I can look at the police report, the more options you tend to have. I handle these cases personally, and the consultation is free and confidential.
Call Crudo Law at (858) 622-7280 or reach out through our contact page. You can also read more about my approach to DUI defense on the about page. Let's figure out your next move together.