The Laws of Nature and of Nature’s God?

We are great fans of Professor Eugene Volokh and of his largely law-related site The Volokh Conspiracy. There was a time when we aspired to become non-Volokh members of the Conspiracy like the pseudonymous Juan non-Volokh.
Lately Professor Volokh has been writing about the Supreme Court’s Lawrence decision and related issues such as gay marriage and polygamy. On these issues, Professor Volokh speaks from a highly intelligent libertarian perspective that seems to me oblivious to the rational ground of moral judgment.
Yesterday, for example, Professor Volokh rejected arguments distinguishing same-sex “marriage” from the marriage of man and woman on the ground of nature, suggesting that nature cannot supply the ground of moral judgment. Professor Volokh asks: “What exactly does ‘unnatural’ mean, and why does it tell us anything about what is proper?” He follows his question with a sophisticated rejection of nature as the standard of judgment.
I wrote Professor Volokh to ask him what he thought of the proposition that men are endowed “by nature” with “certain unalienable rights” among which are life, liberty, and the pursuit of happiness. Unfortunately, he has posted an advisory warning on his site: “GAY MARRIAGE E-MAIL: I’m afraid I’ve been getting so many messages on gay marriage that I might not be able to personally respond to all of them; my apologies for that.” Consistent with the advisory, Professor Volokh has reponded to my inquiry, “Sorry, swamped, have to pass.”
I’m afraid that impending developments will provide occasion for us to return to this subject.