The Washington, DC Code and city regulations allow the police to set up drunk driving checkpoints within the District of Columbia. A DUI checkpoint is when the police will set up a roadblock and randomly stop cars to perform a sobriety check on the driver. In Washington, DC, the DUI checkpoints are usually set up in locations and at times when there a likely to be a greater number of drunk drivers on the roads, such as just after the bars and nightclubs close.
Normally, the police must have probable cause to stop a driver on suspicion of drunk driving. This may involve weaving, driving erratically, failure to obey posted signs or traffic lights, or other similar behavior. In the case of a sobriety checkpoint, the police are allowed to pull over drivers who are driving under the influence of alcohol or drugs without probable cause. However, the law requires that the police create a standardized operating procedure and follow that procedure at all times while operating the checkpoint. The MDP will decide beforehand to pull over every nth vehicle. For example, they may decide to pull over every 5th vehicle to perform a sobriety check. This means that they will pull over one car, perform a check, let four more cars pass through the checkpoint, and pull over the 5th car.
While this may seem simple enough, it can actually be quite complicated to follow. Officers may get distracted or involved with another car and forget which car they are supposed to pull over. They may resort to a completely random order, or choose cars they think are more likely to have drunk drivers. This is a violation of your rights, and the DC police are not allowed to do this.
If you have been pulled over at a sobriety checkpoint in DC and charged with a DUI, DWI, OUI, or even other crime, your lawyer may be able to challenge the operation of the checkpoint in court and possibly get evidence excluded and charges dropped.