Generally, police officers must have probable cause to stop a driver on suspicion of DUI. Thus, they must observe some indication, however minimal, of impairment, recklessness or violation of traffic rules.
However, the law also allows sobriety checkpoints, where police officers put up a roadblock and require passing vehicles to stop at random. There, they check license and registration and observe whether the motorist presents any signs of intoxication. If they suspect DUI, they typically proceed as they would during a regular DUI stop.
Legal requirements for checkpoints
To protect the rights of Kentucky drivers, the law also sets down certain rules for these checkpoints. First, supervisory officers must determine the times and locations of checkpoints, which should not unduly obstruct traffic and should relate to the conduct the checkpoint seeks to reduce. Thus, a checkpoint near a bar and restaurant district is more likely to be reasonable than one on a remote country road where no DUI incidences have arisen recently.
Next, the officers manning the checkpoint must follow established procedure for conducting random, neutral stops. They may not target specific types of vehicles or drivers and must conduct each stop the same way.
The checkpoint may not operate as an ambush; police officers must make the presence of the roadblock obvious. This includes the presence of uniformed officers and patrol cars with flashing lights. Generally, law enforcement should also publicize a planned checkpoint in advance and post signs in the area leading up to the block.
Finally, the initial stop must proceed quickly. Typically, the officer should only take a few seconds to glance at a license and registration and decide whether there is reasonable suspicion of intoxication; if so, the officer should pull the driver to the side before proceeding with further questions or sobriety tests.
When you run into a checkpoint, you likely have no way of knowing whether it is operating in full compliance with legal requirements. However, if a subsequent investigation shows noncompliance, it can serve as a basis for a strong defense.