Apparently they are not ADR aproved, as far as i know. I am not sure about this, correct me if im wrong but all clear tail lights (alltezas) that are not standard from the manufacture of the car are illigal.
Correct me if im wrong again.
Also i think it has something to do with the reflector in the light. It being white/clear causing it not be viewable.
Correct me if im wrong on this aswell.
The light covers being clear apparently confuses other drivers (doesnt confuse me) cause the light cover doesnt tell where the brake light is until you use the brakes which is supose to cofuse other driver.
Now im not 100% sure on the rules but wat i wrote above is what i ruffly remember being told by my cuzn (coppa) cause i wanted clear on my car ages ago, but apparently they look crap on regency red.
Hope this helps you guys out