In 2004, Sean Bailey recalls, he was driving through the streets of St. Louis County en route to a party, when he saw a familiar black-and-white car out of the corner of his eye. He reached for his phone to warn the friend he was following to slow down, but it was too late; the cop blared his siren and pulled up behind him. Bailey, who had a warrant stemming from a failure to appear in court for unpaid traffic tickets, felt a familiar pang of anxiety. He knew exactly what was going to happen next.