Arkes and O'Brien on Natural Law

There has been, during the last few days, an interesting exchange going on at Public Discourse regarding Prof. Hadley Arkes's account of natural-law ethics (set out in, inter alia, his new book, "Constitutional Illusions").  Here is Matthew O'Brien's review of the book;  here is Arkes's response; here is O'Brien's reply.

I'm not competent to say much about whether, for instance, Arkes's view is, or is excessively "Kantian".  (Here's hoping our own Robby George will weigh in!).  I do have questions, for what it's worth, that the role Arkes envisions for federal judges in identifying and applying natural-law principles in the context of constitutional adjudication.  For more on this question, see (again) Patrick Brennan's recent review, and my response.