Thanks to Greg Alexander, Akhil Amar, Will Baude, Aaron Bruhl, Michael Dorf, Joey Fishkin, Marin Levy, Bernadette Meyler, David Pozen, Catherine Roach, and Steve Sachs for helpful and thought-provoking comments on earlier drafts, and to Kevin Jackson for excellent research assistance. Any remaining errors or infelicities are, of course, my own.