It's one thing to say that a law still applies even if you didn't know about it, but it's another thing to say that someone who knew the law and took active steps to make sure the law wasn't being broken (like verifying age on a birth certificate) is still guilty.  I think that's going a bit overboard.  Indeed, how is anyone ever supposed to have any sort of sex?  Since age verification doesn't protect you, how can you ever be sure you're not breaking the law:P

~tallman