i always heard similar about being able to drink with your parents being OK.. i always thought it was more of that, 'if its only in our house, whos going to know' sorta thing, not actual law, of course i have never really looked into it either. when it comes to yellow/red lights, i know its legal to go through an intersection on yellow, take left turns while yielding to an oncoming green for ex. if you go halfway out into the intersection and the light turns yellow, you cant just stay there! at least in PA, i think situations like that are more the reason for being able to use yellow to clear the intersection, because yellow light durations are regulated here. when putting a light in, theres a whole bunch of equations that are used to calculate a safe duration for the light to be yellow based on how far away you are when you can first see the light, speed limit on the road, size of the intersection etc. lights are very rarely set up to those specifications though, so if you ever get busted for 'running' a red light, look into that. if you can prove the yellow wasnt long enough, they cant charge you (thats how i learned about all of that stuff, my roommate is a civil engineer and got pulled over for running a light, so i helped him go out and take measurements of the intersection for the calcs.)