The Warren Court had a complex relationship with policing. On the one hand, it appeared to act as a regulator of police practice, but on the other hand, the Warren Court supported discretionary police practices in opinions that, now 50 years later, reveal themselves as the starting point for the Supreme Court’s ultimate deregulation of policing. Two opinions in particular, Pierson v. Ray, studied in conjunction with Terry v. Ohio, offer a window into the birth of the “reasonably unreasonable” officer who operates with relative impunity on the streets today.