We're missing "the
third observer's opinion".
But still, the U.S. Supreme Court has heard countless arguments on police powers over this ½-century: Through this winnowing process, the system has evolved to our present laws regarding the "police stop" in general.
Those Supreme Court scrutinies now more-fully respect LEOs' reasonable right to self-protection during stops.
Due to the increased rate of violence nationally, any alteration in Supreme Court scrutinies that increases the dangers to enforcement officers would have effects on public safety far more profound than one could imagine. IMHO. 
That's my opinion: do I hear an "Amen"?
