Pennsylvania Senator Rick Santorum commented a few months ago that if the Supreme Court manufactured a constitutional right to consentual sodomy in overturning Texas' sodomy laws, "then you have the right to bigamy, you have the right to polygamy, you have the right to incest, you have the right to adultery."

Of course, he was widely pilloried as an ignorant bigot. However, Jonah Goldberg's column today (which is a mixed bag of some excellent and some not-so-excellent stuff) provides a link to a fascinating column by Slate's William Saletan. I had not previously seen Saletan's piece, which was published in April, in which he desperately tries to get a straight answer (no pun intended) from the Human Rights Campaign to Santorum's charge, to no avail.

Keep in mind, Saletan is no raving conservative. In fact, he generally believes that homosexual marriage is appropriate. But the question that Santorum was addressing (as well as the Supreme Court) was whether there was a Constitutional right to such behavior.

Saletan says:

Let's leave adultery and polygamy out of it for the moment. Let's set aside morality and stick to law. And let's grant that being attracted to a gender is more fundamental than being attracted to a family member. Santorum sees no reason why, if gay sex is too private to be banned, the same can't be said of incest. Can you give him a reason?

And as it turns out, the answer (at least for the Human Rights Campaign) is "no." The first-blush answers do not provide any solace for those who claim to see a legal difference between one consensual sexual practice and another. Says Saletan:

The easy answer—that incest causes birth defects—won't cut it. Birth defects could be prevented by extending to sibling marriage the rule that five states already apply to cousin marriage: You can do it if you furnish proof of infertility or are presumptively too old to procreate. If you're in one of those categories, why should the state prohibit you from marrying your sibling?

Why, indeed? Many, if not most, of us assume incest laws are based on concerns for offspring. But if there are no offspring, what then is the "compelling state interest" for keeping a brother and sister unmarried? Saletan didn't have much luck finding out from the Human Rights Campaign, though they insist that there is a difference:

On Wednesday, I asked [David] Smith [communications director of the HRC] that question. "We're talking about people; they're talking about specific acts," he said. "It has nothing to do with these other situations that are largely frowned upon by the vast majority of Americans." Is being frowned upon by the vast majority of Americans an acceptable standard for deciding which practices shouldn't be constitutionally protected? "It's not part of the discussion," Smith replied. I asked whether it was constitutionally OK for states to ban incest. "Yes," he said. Why? "There's a compelling interest for the state to ban that practice," he said. What's the compelling interest? For that, Smith referred me to HRC General Counsel Kevin Layton.

The HRC is on the horns of a dilemma here. If they were to just come out and say that no, there would be no compelling state interest in preventing such incest, they will have proven Santorum's exact point. Their entire attack on Santorum was based on his supposedly "ignorant" statements which supposedly "equated" homosexuality with incest.

But Santorum's point was a legal one. And when asked for a legal differentiation between homosexuality and consentual incest, even the communications director for the Human Rights Campaign is spectacularly unable to provide one, instead shuffling Saletan off to talk to the lawyers. But the lawyers proved as unable to provide a distinction as David Smith was. After some back and forth,

Essentially, Layton reasoned that it isn't his job to explain why incest and gay sex are different. It's Santorum's job to explain why they're similar.

And yet again, Santorum, the guy who seemed so obviously wrong, turns out to be the guy who was exactly right.