You can refuse a field sobriety test in Missouri. No state statute requires you to walk a line, stand on one leg, or follow a pen with your eyes at the roadside, and declining those exercises carries no automatic license penalty. Refusing is not a shield against a DWI arrest, though, and the choice has real trade-offs worth understanding before an officer ever asks.
Why Refusal Is Legal
Field sobriety tests are investigative tools, not legal obligations. Missouri’s implied consent law, the statute that requires cooperation with certain tests, applies only to chemical tests of your blood, breath, or urine administered after an arrest or qualifying stop.1Missouri Revisor of Statutes. Missouri Code 577.041 – Refusal to Submit to Chemical Test No parallel statute covers roadside balance and coordination exercises. An officer can ask you to perform them and will usually encourage cooperation, but the request is just that.
The consequences line up with that distinction. Say no to a field sobriety test and nothing automatic happens: no license revocation, no administrative hearing, no separate charge. Say no to a post-arrest chemical test and Missouri revokes your license for a full year.2Missouri Department of Revenue. FAQs – Refusal to Submit to an Alcohol and/or Drug Test The two refusals look similar from the driver’s seat and carry wildly different costs.
What Refusing Doesn’t Protect You From
Declining the roadside tests does not make a DWI arrest impossible. Officers build probable cause from everything else they see and smell: alcohol on your breath, bloodshot eyes, slurred speech, an admission that you had a drink or two, open containers in the car, the driving behavior that triggered the stop. If those observations stack up, the arrest happens whether or not you ever tried to walk heel-to-toe.
Your refusal can also surface at trial. A prosecutor is free to argue that you declined the tests because you knew you would fail, framing the refusal as evidence you were aware of your own impairment. The argument is circumstantial and does not prove intoxication on its own, but it gives the state another piece to work with. Whether that risk is worth it depends on your situation. Someone sober who has a bad knee, an inner ear condition, or any of the dozens of ordinary problems that make a one-leg stand hard may be better off refusing a test they would fail for reasons that have nothing to do with alcohol.
How to Decline During the Stop
Pull over safely, turn off the engine, keep your hands visible, and stay calm. You are legally required to produce your license, registration, and proof of insurance when asked. That part is not optional.
What you say beyond that is up to you. You do not have to answer questions about where you have been, where you are headed, or what you have had to drink. Volunteering “just two beers” hands the officer evidence of alcohol consumption and strengthens probable cause. A polite “I’d prefer not to answer that” is enough.
If the officer asks you to perform field sobriety tests, you can decline. Say it clearly and respectfully. “I respectfully decline” works. Do not argue, do not run, and do not get drawn into a debate about whether you should cooperate. The decision is yours to make and the officer is not required to agree with it.
The Post-Arrest Chemical Test Is Different
Confusing a roadside exercise with the post-arrest chemical test is the costly mistake. Missouri’s implied consent law treats breath, blood, and urine tests administered after arrest as something you already agreed to by driving on Missouri roads. Refusing one triggers an immediate one-year license revocation known as a Chemical Revocation.2Missouri Department of Revenue. FAQs – Refusal to Submit to an Alcohol and/or Drug Test
Before the test, the officer must explain why it is being requested and warn you that refusal will revoke your license and can be used against you in court. If you ask to speak with an attorney first, you get 20 minutes to make contact. Still refuse at the end of those 20 minutes and Missouri treats it as a refusal.1Missouri Revisor of Statutes. Missouri Code 577.041 – Refusal to Submit to Chemical Test If you are arrested and offered a chemical test, use that 20-minute window. The calculation at that point is not the same as the one at the roadside.
Preliminary Breath Tests
There is one more roadside device worth sorting out. Missouri law authorizes officers to administer a portable breath test before placing you under arrest. This preliminary breath test is not the post-arrest chemical test covered by implied consent, and the statute explicitly says the implied consent rules do not apply to it. Its numerical result can be used to establish probable cause for an arrest, but it cannot be introduced in court as proof of your actual blood alcohol level.3Missouri Revisor of Statutes. Missouri Code 577.021 – Chemical Tests Prior to Arrest
Practically, that puts the preliminary breath test in the same category as the field sobriety tests. Refusing it carries no automatic license penalty. The test that does carry mandatory revocation is the formal evidentiary breath, blood, or urine test given after arrest, usually at a station or hospital. If an officer is handing you a small device at the side of the road before you have been arrested, you are looking at the preliminary version.
A Note for Commercial Drivers
If you hold a commercial driver’s license, the stakes change. Federal regulations set the impairment threshold for commercial vehicle operators at a blood alcohol concentration of 0.04%, half the standard limit. A first DWI conviction or chemical test refusal typically results in a one-year CDL disqualification, and a second offense can trigger a lifetime disqualification. Those federal consequences apply on top of whatever Missouri imposes on your regular driving privileges, so a CDL holder has more reason to think through every decision during a stop.
If you are arrested, state clearly that you want to speak with a lawyer before answering further questions, and use the 20 minutes the chemical test statute gives you to try to reach one.