there are certain headlight covers that they will make you take off on a trail if there is a road block. yellow, red and i think blue. we were riding in tughill 2 yrs ago and there was a road block for insurance cards and the cop made my buddies take off there headlight covers, yellow and red cause he said it resembles a cop sled coming down the trail but that doesnt mean you cant put it back on down the trail.
and i know, the green ones anyways, dont effect the brightness of your headlights. i can see what you're saying, but the covers dont really effect the light that much,or they wouldn't make them.
i think they should have that law posted a little better. makes sense though, if you think about cars. you cant have those color lights, or strobes here. then again, all you have to do is puit them back on andnext time you'll get stopped the other cop wont care.