My Imaginary E-TAGGER

This might sound far fetched but technology is moving very quickly.

Lets say you're driving along and the car in front of you suddenly stops to turn, no signal and you have to brake hard not to hit him. Use to be there wasn't much you could do about it other than call him a few bad names.
But now you can TAG him electronically. There could be different degrees like from minor danger to extreme danger. What good would that do? When a cop pulls you over he could run your E-TAGS. This could help them to decide to give you a ticket or let you off with a warning. I guess e-taggers would have to have some kind of I.D. associated with the car it came from. To prevent you from repeatedly tagging someone you don't likes car. Since it would be completely up to the individual whether or not to E-TAG, that shouldn't be a problem.

This would also give you a good excuse to not let people borrow your car.