PhDs in Law?

Over at PrawfsBlawg Orly Lobel (San Deigo) provoked an interesting discussion (here) about the efficacy of creating a Ph.D. in law (presumably run by law schools).  Incident to Sarah's earlier post about law schools' increased appetite for Ph.D.s (here), I am curious about folks' take on Lobel's argument that (some) law schools should contemplate gearing up for a Ph.D. program in law (as well as Lobel's point that such a development could have "transformative effects" on law schools).  As a distinct--though related--aside, recall Vanderbilt's recent hiring of Kip Viscusi (and Joni Hersch) and decision to create a Ph.D. program in Law and Economics (described here).