Legality of having sex in your car.

[evilbutterfly]

This is a weird question that I can't seem to find the answer to. I've searched around the internet and can only find articles about the dogging problem in the UK. It seems to be legal there to have sex in your car (wikipedia mentioned specified places just for dogging), but every TV show or movie I've ever seen has portrayed car sex as illegal. A cop always seems to show up and make them stop.

My question though, is it really illegal to have sex in your car by the side of the road? I mean, as long as you're pulled over and not blocking traffic, and if you're low enough down that it can't count as indecent exposure, what's the problem? Unless there are specific laws that ban it, I don't see how it could be illegal.

So if anybody could tell me whether or not it's legal and give me some evidence (like a .gov site that lists it as illegal, maybe) so I know for sure, that'd be nice. I just can't find out on my own. =\