You don't even really need to be a teen nowadays!
The other night I was watching the news and there was a thing on there where a nine year old boy raped a four year old girl. The mother actually walked in on the boy pulling his erection out of his sobbing little sister!
I think anyone who would look at that and not find that morally and ethically repugnant should have their head examined.
That said...
I first discovered my submissive side when I was in high school. I was fouteen and Chris was eighteen, and we'd fool around in the library after school when we were working on the school newspaper. That was as far as I wanted to get; he'd use backpack straps to tie my hands while I sat on a chair and he'd duck under the table and play with my cunt. One afternoon he went a little too far. He pulled me out of my chair and turned me around, pulling my panties down, and started to enter me. I told him no, told him to stop, and he didn't. He said i liked being tied up and made to do dirty stuff (it was a parochial school, after all, and Catholics take a very dim view of fornication)and so I must want this too. He proceeded to divest me of my virginity, and it was PAINFUL! I did everything I could to get him to stop, but he didn't.
The point I'm trying to get at here, though, is that whether we like to think about it or not, teenagers (and, judging from the news, little kids too) engage in sex. To deny that would be to deny a basic fact of nature. Back in the caveman days, as soon as a girl had her first period she was married off to some cro-magnon who took her whenever he wanted to, and by the time she was eighteen, she'd have a toddler on each leg and a baby on her hip. (Imagine that. I had my first period when I was seven. By the time I was eighteen I'd have had at least five or six babies!)
Anyway, back on topic. Teens have sex. Like rabbits, if my senior class were any sign. They explore their bodies even as they start exploring the world (by getting jobs) and explore the limits of their parents' tempers (anyone with teens, or who has kids who were once teens, will understand.) While our current societical expectations are that they will wait until they are 'legal', there are very few teens who actually do wait. Therefore, i really don't think that the government banning teen/older person literature, photos, and other media is really going to make any difference whatsoever. And i think maybe they realize that. It's kind of like sticking your finger in a little hole in the dyke while watching water pour out of a big gap further down the wall! But they still try to stop it because some little piece of their minds is insisting that mother nature's implanted urge to explore the body is wrong.