People in Arizona may notice that, especially around holidays such as Labor Day, the Fourth of July and New Year's Eve, police in the state set up checkpoints in order to try to identify and arrest drunk drivers. However, even motorists who haven't been drinking can be stopped at these checkpoints. They may wonder, then, if such checkpoints are even legal.
The United States Supreme Court determined in 1990 that it is legal for police to set up DUI checkpoints. Although the Fourth Amendment protects individuals from unreasonable searches and seizures, DUI checkpoints did not violate this law. This is because there are circumstances in which a search will be considered to be reasonable, even if police do not have a warrant. Usually this is the case if police have probable cause to believe the search is needed. One example of this is searches during an arrest, as there is probable cause to think that the individual being arrested has broken the law.
This brings us to DUI checkpoints. It should be noted that if police pull a driver over, this constitutes a seizure, as the driver is not free to leave until the police say so. And, while it may seem like pulling over every driver at a checkpoint, whether they seem to be drunk or not, does not constitute probable cause, this is not the case. This is because the Supreme Court has stated that the need of the state to stop people from driving under the influence was greater than the minimal intrusion a DUI checkpoint had on sober motorists.
All of this being said, it is important to keep in mind that determining whether a seizure violated the law is still a complex question. Drivers who are facing DUI charges after being pulled over at a checkpoint may want to seek the help of an attorney, who can assess the situation and determine whether the law was broken.
Source: FindLaw, "Are DUI Checkpoints Legal?," Accessed Aug. 28, 2017