Taken from the www.lamin-x.co.uk/faq.htm
Our coloured/tinted headlamp protection films may not be legal for road use on primary lighting in your country. An off-road use disclosure is hereby declared. Please check your local laws before application if you have concerns. Installation of our tinted protection film on your primary lights is done so at your own risk.
The law/Mot hand book within the UK states that front primary lighting must produce a White or Yellow light. There is no documentation about the colour of the actual lens.
Our Clear/SubtleTint/GunSmoke/OpticBlue light protection films all produce a legal natural light colour, and our Yellow produces a Yellow tinted light which is of course legal within the UK.
None of our light protection films change/adjust the beam pattern or cause insufficient light output.
After reading their web site I think its down to the general interpretation/judgment call of the police. (and hey I aint arguing with my cousin lol)
But as with all things when people actually tint their headlights which do effect the output of white or yellow light the police are gonna start pulling everyone if it looks even remotely dubious lol.
It's like being pulled over because you have your front fog light on to look cool hehe. It aint illegal but the police don't like it so they pull you over and give you a hard time (or does that just happen to me )
The way I see it is, if you and your car are road legal, who cares if they pull you over, you did nothing wrong lol.