Hah, law. As if any fourteen year olds about to have sex suddenly stop and think "HOLD IT THIS IS ILLEGAL WE CAN'T". You're saying that teens this young arn't responsible enough to decide to have sex or realize the consequences that could result from having unprotected sex. You assume however that they're responsible enough to think of the legal consequences that would result if the act were illegal.

I've known plenty of stupid girls who have made stupid decisions, but most of them were still primarily concerned with getting pregnant from having sex as opposed to breaking the law.

Then comes the issue of what age you should be until you can 'responsibly' decide to have sex. Is it 13, 14, 16, 18 or is there no definitive age at all? To determine whether you are responsible enough to have sex would mean you take the precautions to protect yourself against pregnancy or STDs. But plenty of adults have unprotected, irresponsible sex as well, should it be illegal for them too?