Greasing that slippery slope all the way down to "heroin-induced necrophilia."

The Volokh Conspiracy asks the obvious questions about adult incest pace the Lawrence v. Texas decision:

(1) Should it be illegal, and, if so, exactly why? Is it just because it’s immoral? Because legalizing incest would, by making a future sexual relationship more speakable and legitimate, potentially affect the family relationship even while the child is underage (the view to which I tentatively incline)? Because it involves a heightened risk of birth defects (a view I’m skeptical about, given that we don’t criminalize sex by carriers of genes that make serious hereditary disease much more likely than incest does)?


(2) Given Lawrence v. Texas — and similar pre–Lawrence decisions in several states, applying their state constitutions — what exactly is the basis for outlawing incest? Is it that bans on gay sex are irrational but bans on adult incest are rational, and rationality is all that’s required for regulations of adult sex? Is it that bans on gay sex don’t pass strict scrutiny (or some such demanding test) but bans on adult incest do? Is it that Lawrence rested on the fact that bans on gay sex largely foreclose all personally meaningful sexual relationships for those who are purely homosexual in orientation, whereas incest bans only foreclose a few possible sexual partners? UPDATE: For court cases on this, see here (stepfather-stepdaughter) and here (brother-sister).

And if adult incest is hunky-dory, then why not incestuous marriages?

Or necrophiliac marriages?

Once again, let's thank liberalism for raising questions that don't deserve to be raised.