Running a red light is an offense that can have catastrophic consequences. According to the Insurance Institute for Highway Safety, more than fifty percent of all Americans admit to running red lights, and it’s the leading cause of urban crashes. What Classifies as Running a Red Light? While each jurisdiction may define it differently, it typically means vehicles entered an intersection after the traffic signal changed to red. Depending on the state, the law may follow permissive yellow regulations. This means drivers who entered the intersection while the light was.