The recent arrest of a liberal Columbia professor and Puffington Host contributor for incest (an apparently consensual relationship) with his adult daughter has several people talking about sexual taboos and the law. This also comes up during discussions about gay marriage, and brings up the fundamental question about how much the state should be involved in sexual matters entirely.
In both cases, the issue of what the government should endorse, should tolerate, and should prohibit is the key. And those are three very important distinctions.
By "endorse," I mean "legally accept and recognize." This is for marriage and other matters that involve legal recognition.
By "tolerate," I mean not specifically say anything positive or negative -- simply by not making laws against it.
And by "prohibit," I mean specifically writing laws against it.
Incest is one of the points raised in the debates about gay marriage. If we allow two men to marry, why not two relatives? The genetic issue of inbreeding can be addressed by making it a same-sex couple of relatives, so why not outlaw them?
Historically, the answers have been tradition and the Bible. The Good Book (in Leviticus, I believe, among other places) spells out what are acceptable and unacceptable sexual relations and practices, and that part of the Bible is accepted by Christians, Jews, and Muslims, so it covers pretty much the majority of Americans.
But "tradition" and "the Bible" have no legal standing under the Constitution. They simply can't be cited as authoritative sources in court.
So I've batted around my own test for such matters, and while I haven't completely thought it through, I think it works in most cases. I call it the "consenting adults" test.
Essentially, I believe that whatever involves just consenting adults, and does not do violence to others or society as a whole, should be tolerated. And, when it involves the notion of legal equality, it should be accepted.
Gay marriage: Sure. Fine. Whatever. "I think it's gross" is NOT sufficient legal justification for banning it.
Pedophilia: Not consenting adults. Forget it.
Bestiality: Animals can't consent. Nope.
Incest: No, no, a thousand times no. In some cases, it involves minors -- so there goes the "consenting adults." In others, it raises the likelihood of inbreeding -- so there goes the "harm to others." In some, involving parents, squicky issues of power and authority and inequality are raised. But even in those cases where those pitfalls are avoided, the introduction of the sexual dynamic entirely within the family structure causes violence to society as a whole. So no.
Bigamy: Too many legal nightmares. Let's take the case of Adam, Eve, and Eden. Adam marries Eve, and then the two marry Eden. Then Adam wants out. What does that mean to the legal relationship between Eve and Eden? Are they still married, even if they don't want to be? Are they divorced from each other, even if they don't want to be? And what about children?
Marriage is a straight line (pardon the expression), defined by two points. It can be made and broken relatively simply (geometrically speaking). Introducing more points, making it into triangles, squares (with corners also connected), and whatnot just gets messy. No just say no to bigamy.
It's not a perfect system, this little notion of mine. But it does manage to address the... er... sticky issue of sex and the law, with a slightly vague but clearly definable principle that is not rooted in religion or tradition, but reason and logic and common sense. And it's not drawn from them, but instead demonstrates that the religious strictures did have some common sense to them.