I had an exchange with someone who was responding to my saying that alcohol prohibition to teens is based on arbitrary age criteria. They wondered how I saw other age "laws" and asked:
"When is someone old enough to have 'consensual' sex? I don't doubt a lot of 6-year-olds have consented to sex with a preacherman promising heaven. I know you don't think it's a law-enforcement issue, but when does the parent respond to this supposed aggression, and how? What about consenting 13-year-olds? Can I kill the boy if he's doing my daughter? What about a 17-year-old with a 12-year-old?
"Or we can talk about hard drug use. Is it OK if I stay high on crack all week and don't feed my 3-year-old? Can I give him some, too? It's my kid and I should be allowed to decide the best way to raise him. Who has the authority to say I can't do this? And again, at what age is the child old enough to decide for himself?"
Yeah, tough questions. Here's the way I look at it:
I don't think there is a one-size-fits-all age for consensual sex (or anything else).
I don't believe 6 year olds are able to consent to sex, because they don't understand what they are consenting to. You start getting into the teen years and I think it's strictly a case-by-case issue. Probably some 13 year olds do know what they are consenting to, and are ready to accept the consequences, but most aren't. By 16 or so, I'd start assuming they can consent, without definite evidence to the contrary. I'd always rather err on the side of liberty and respecting the other person's rights and choices.
I never think killing someone is a good "solution" to sex, except in the case of forcible rape. I can understand the protective parent rage, even if I think it's always an overreaction. Which would damage your daughter worse? Having sex at 13, or seeing her dad murder her 17 year old boyfriend who she had just had sex with?
Again, I don't think all-encompassing laws are a good way to sort it out. If The State can try "minors" as adults for crimes, then obviously even the "law" accepts that some can act as adults in some cases, which necessarily includes being able to consent to sex, even if the law doesn't want that street to run both ways. You can't allow only negative outcomes but forbid the neutral or positive ones.
I also believe parents have an obligation to protect their kids, but they don't own their kids. "My daughter" is an expression of relationship, not of ownership (which applies to the drug use example below, too). Emily already makes choices I disagree with, and letting her make some of those will (I hope) teach her that actions have consequences, and that my advice is given for her benefit. I also admit to her when I am wrong.
My older kids make a lot of choices I disagree with, but they are adults and I am here to listen when things go wrong.
For that matter, I make choices I disagree with and live with the consequences.
If you stay high on crack and don't feed your 3 year old- and I find out about it- I would probably come to the kid's rescue- with friends, if I think you might protest. Yes, I would trespass, just like I would if I saw someone being raped on private property. I'll admit I had no right to do so, and seek forgiveness, but I'd accept the consequences without hesitation to save someone. Again, this comes back to the fact that parents don't own "their kids"; the kids own themselves, even if they aren't able to take complete responsibility for themselves yet. You can decide the best way to raise your kid as long as you don't violate his rights, which are equal and identical to your own rights. As each kid gets older, they will have more ability to decide for themselves as they understand more fully the consequences of their choices, but that timeline will vary from individual to individual rather than following a legal schedule. Some people never "mature" enough to accept their consequences, but still, no one has the right to run their life for them. All you can do is defend yourself from them.
No one has "authority", but some can take responsibility. And, unfortunately, this is the real world and nothing will save everyone. Nothing will prevent every tragedy. I still prefer the promise of liberty over the tyranny of "for the children", even when the child they pretend to protect is mine.