Drivers who see a DUI checkpoint are not required to proceed through it. Simply turning to avoid a checkpoint does not provide police with a good enough reason to take action, but they may pursue the vehicle involved if they observe it being driven erratically or making an illegal turn. When vehicles do approach a checkpoint, police usually only ask drivers a few questions and examine their driver’s licenses, registrations and insurance documents, but they may conduct searches if they detect the odor of marijuana or see evidence like open containers of alcohol or illegal drugs in plain sight.
When police officers at a DUI checkpoint suspect that a driver may be operating his or her vehicle while under the influence of drugs or alcohol, they may ask the driver to perform a standardized field sobriety test or provide a breath or blood sample for toxicology testing. Police often make these requests when drivers are incoherent or show signs of intoxication such as glassy or bloodshot eyes and slurred speech.
When motorists who enter a DUI checkpoint are charged with drunk driving, the most important pieces of evidence against them are usually blood or breath test results. Experienced criminal defense attorneys may study this evidence carefully to ensure that blood samples were handled properly and breath tests were conducted using well-maintained and properly calibrated equipment. If these efforts reveal that shortcuts were taken or mistakes could have been made, attorneys may seek to have DUI charges dismissed.