Ya, it is required on US vehicles to have a certain portion of the turn signals to have an amber reflector. similar law for the rear. But depending where you live the police may or may not notice or care. Where I lived in florida, they cared. They'd pull you over for 2mph over the limit. here where I live now, they don't care much so long as you're not doing more than 5 over or endangering others.. I hear the town next to ours (5 miles away) have meticulous police. So don't get rid of your old OE set if you get the clears.. and if you install blue bulbs, you're more likely to get pulled over. if it'd a yellow or white bulb, they probably would never notice your missing amber reflector piece. I've dabbled in this topic with some other cars I had/have.