As long as the officer had a legitimate reason to pull the driver over in the first place, this is not a particularly controversial way for police to enforce Pennsylvania’s DUI laws. A traffic stop for something else, such as speeding or running a stop sign, can lead to a DUI investigation if the officer suspects that the driver is impaired. A police officer might pull a car over because they thought the driver was driving suspiciously. Driving under the influence (DUI) cases in Pennsylvania often begin with a traffic stop.
