In California, you can refuse a field sobriety test if you are 21 or older and not on DUI probation, and the refusal alone will not cost you your license or trigger a fine. These roadside exercises are voluntary for most adult drivers. The important catch is that California law also classifies the handheld roadside breathalyzer as a field sobriety test, and two groups of drivers are required to take it: anyone under 21 and anyone currently on DUI probation. And none of this applies to the chemical test given after a lawful arrest, which is a separate obligation with serious penalties for refusal.
What a Field Sobriety Test Is
Field sobriety tests are the physical and cognitive exercises an officer uses at the roadside to look for signs of impairment. The three standardized tests developed by the National Highway Traffic Safety Administration are the Horizontal Gaze Nystagmus test, which tracks involuntary eye jerking as you follow a moving object; the Walk-and-Turn test, which asks for heel-to-toe steps along a line; and the One-Leg Stand test, which requires you to balance on one foot while counting aloud.
What catches many drivers off guard is that the handheld preliminary alcohol screening device, the small breathalyzer an officer may offer you at the roadside, is also a field sobriety test under California Vehicle Code 23612(h). It is not the formal chemical test. The statute treats it as an investigative tool, and the same voluntary rules that cover the walk-and-turn cover the roadside breath device too.
When You Can Say No Without Penalty
If you are 21 or older and not on DUI probation, every field sobriety test an officer offers you at the roadside is voluntary. That includes the physical exercises and the handheld breath device. No California statute penalizes you for declining, and officers are not required to tell you the physical tests are optional. For the roadside breathalyzer specifically, the officer actually is required to tell you that you can refuse and that blowing into the handheld device does not satisfy your separate obligation to submit to a chemical test after arrest.
A polite “I’d prefer not to take the tests” is enough. You do not have to explain yourself.
Refusing does not end the stop, and it does not make you arrest-proof. If the officer pulled you over for swerving, smells alcohol, or hears slurred speech, those observations alone can supply probable cause for a DUI arrest. What declining does is keep you from handing over additional evidence. The exercises are designed for controlled conditions, and roadside reality, with uneven pavement, passing traffic, and nerves, can make a sober person look impaired. Roadside breath devices are also less accurate than the station machines, and their readings generally are not reliable enough to stand alone as trial evidence, though they can give an officer the reasonable cause to arrest.
Who Cannot Refuse the Roadside Breath Test
Two groups of drivers face mandatory preliminary alcohol screening, and refusing carries real consequences.
Drivers Under 21
California’s zero-tolerance law makes it illegal for anyone under 21 to drive with a blood alcohol concentration of 0.01 percent or higher. Under Vehicle Code 23136, an underage driver is deemed to have already consented to a preliminary alcohol screening test if lawfully detained on suspicion of violating that limit. Refusing the test, or failing to complete it, results in a license suspension or revocation of one to three years.
Drivers on DUI Probation
Vehicle Code 23154 applies the same zero-tolerance standard to anyone currently on probation for a DUI conviction. If you are on DUI probation and lawfully detained for a suspected violation, you are deemed to have consented to the preliminary alcohol screening test. Refusing triggers the same one-to-three-year suspension or revocation.
For both groups, the roadside breath device is not optional in the way it is for other adults. Officers do not always clarify which category a driver falls into, so knowing your own status before you drive matters.
After Arrest, the Rules Change
The legal stakes shift sharply once you are placed under arrest. California’s implied consent law, Vehicle Code 23612, provides that anyone who drives on California roads has already given consent to chemical testing of blood or breath after a lawful DUI arrest. This is a completely different obligation from the voluntary roadside exercises.
Chemical tests are the formal blood draws or breath tests conducted at the police station or hospital after arrest. The equipment is more sophisticated and regularly calibrated, and the results carry real evidentiary weight in court. Unlike field sobriety test results, chemical test results can directly establish whether your blood alcohol concentration met or exceeded 0.08 percent.
After a lawful arrest, the officer must tell you that refusing the chemical test will result in a license suspension and, if you are later convicted, mandatory additional jail time. You usually get to choose between blood and breath. You do not get to choose neither.
Penalties for Refusing the Chemical Test
Refusing a chemical test after a lawful DUI arrest sets two tracks of consequences in motion: an administrative action by the DMV and enhanced criminal penalties if you are convicted.
DMV License Action
The DMV suspends or revokes your license based on prior DUI-related offenses or refusals in the past ten years:
- First refusal: one-year license suspension.
- Second offense or refusal within ten years: two-year license revocation.
- Third or subsequent offense or refusal within ten years: three-year license revocation.
These actions happen whether or not the criminal DUI case ends in a conviction. The DMV process runs separately from the court case.
Added Criminal Penalties
If you refused a chemical test and are then convicted of DUI, the court adds mandatory jail time on top of whatever the DUI itself carries:
- First DUI conviction involving injury under Vehicle Code 23153: 48 additional hours in county jail.
- Second DUI conviction within ten years: 96 additional hours in county jail.
- Third DUI conviction within ten years: 10 additional days in county jail.
None of that added time can be stayed or served through alternative programs. The court must impose it. The refusal itself can also be introduced as evidence against you at trial, which is not true of a field sobriety test refusal.
Handling the Stop
Pull over safely, turn off the engine, and keep your hands visible. Provide your license, registration, and proof of insurance when asked. From there:
- Physical field sobriety tests. You can politely decline. No explanation required.
- Roadside breathalyzer. If you are 21 or older and not on DUI probation, you can decline. If you are under 21 or on DUI probation, refusing triggers a one-to-three-year license action.
- Chemical test after arrest. Submit to the blood or breath test. Refusing brings an automatic DMV suspension and, on conviction, mandatory added jail time.
- Conversation. You have the right to remain silent beyond providing identification. Declining to answer questions about where you were or what you drank is not obstruction.
The decision that matters most at a DUI stop is not whether to touch your nose or walk a line. It is knowing which tests you can refuse without penalty and which ones carry serious consequences if you say no.