Yesterday, the Supreme Court decided not to hear a controversial DWI case from Virginia. By refusing to hear it, the Court lets stand a Virginia ruling that police may not pull someone over on suspicion of DUI based solely on a tip, rather than direct observation of suspicious driving.
The vehement dissent by Chief Justice John Roberts raised fear that the court's refusal to hear the case would increase the likelihood of drunk drivers remaining on the road in some states. In his words, not allowing officers to pull drivers over based on a tip will allow drunk drivers "one free swerve."
In the underlying case, a Virginia man was pulled over after an anonymous tip that he was driving while drunk. The officer did not observe any traffic violations, but found the man to reek of alcohol after pulling him over.
The state Supreme Court in Virginia, however, overturned the DUI conviction. It held that pulling someone over based on a tip, without directly observing any dangerous driving, violates the Fourth Amendment's ban on unreasonable searches and seizures.

