Normally, DUI traffic stops happen when a car is in motion, a police officer sees a reason to pull the driver over and initiates a traffic stop. There is a clear set of steps that must be followed, including the officer having reasonable cause to pull the car over in the first place.

DUI checkpoints, on the other hand, skirt that part of the law. Instead of looking for a reason to pull a specific car over, the police just stop every single vehicle that comes through the checkpoint. They can then let drivers through if they appear sober or pull them to the side for further testing if it’s suspected that they may be under the influence.

Is this legal? It’s a hot point of contention in many legal circles. Some states, like Michigan, have determined that these checkpoints violate citizens’ rights by forcing them to endure searches without reason. That state and some others do not use checkpoints.

However, Maryland does use them and considers it legal since the Supreme Court ruled that checkpoints do not violate anyone’s rights as long as the authorities use them properly. There is also the general idea that it is preferable to subject some innocent drivers to a checkpoint if that means catching more intoxicated drivers than to allow those impaired drivers to cause accidents.

Again, this is a controversial process. But, regardless of your personal feelings on the matter, the police do use them and the courts consider them to be legal. Therefore, if you get stopped and arrested at a checkpoint, you need to know the options you have to build a viable defense.