Police have a variety of tactics for identifying drunk drivers. Increased patrols on holidays and weekends tend to be the most common, however many police departments, including those in Missouri, can also employ DUI checkpoints to stop cars passing through an area and check the sobriety of drivers.
Despite a ruling from the Supreme Court supporting the legality of DUI checkpoints in the name of public interest and safety, the constitutionality of this tactic is still hotly debated, to the extent that some states have outlawed DUI checkpoints based on their interpretation of the Constitution. Other states have adopted laws or constitutional amendments at the state level against the use of DUI checkpoints. In total, 12 states prohibit DUI checkpoints.
Given the dubious legality of these checkpoints, it is difficult to know how to behave if you’re stopped at one. The most important thing to remember is that you retain all of your rights in this situation. You may remain silent. You are only required to provide the officer with your license and insurance information. Anything you say may be used against you. If you speak, the officer can claim that you were slurring your words and use that as justification to order a breathalyzer test or to search your vehicle. You are also not required to perform any sobriety tests the officer may ask you to do, beyond a breathalyzer.
If it appears that you may be arrested on DUI charges, it’s best to refrain from speaking to the officers, except to ask for your lawyer, which you are legally entitled to. The less you say, the less evidence the police may gather to use against you.
Some drivers take their rights to an extreme by holding up signs stating their choice to remain silent and their objection to searches, removing the need to even roll down their window. This removes the opportunity for the officer to claim that he smelled alcohol in the vehicle and order further tests. In this approach, license and insurance can be displayed to the officer through the window as well, as it is not necessary to physically hand the officer these documents. This approach may make many people uncomfortable, and some might think such obstinance might raise suspicion from officers. It is, however, an excellent example of how to use your rights to protect yourself, and how far those rights may extend.
Beyond protecting yourself, there are some restrictions placed on police departments to protect the public from the disruptive stops at DUI checkpoints. Police are required to report the time and location of the checkpoint to the public. The location must be marked with advance warning signs to alert drivers to its presence. Officers present at the checkpoint must be in uniform, and are not allow to stop vehicles arbitrarily. Finally the checkpoint must be justified as promoting public safety.