9. Professors Wright and Kane have said: “It is impossible to overstate the importance of the Eriedecision.” Wright & Kane, Law of Federal Courts 376 (7th ed. 2011). Reactions to the Erie decision voiced shortly after it was handed down include Shulman, The Demise of Swift v. Tyson, 47 Yale L.J. 1336 (1938); and Tunks, Categorization and Federalism:

“Substance” and “Procedure” After Erie Railroad v. Tompkins, 34 Ill. L. Rev. 271 (1939). Over time, comments about Erie have ranged from “ ‘transcendently significant,’ ” Nelson, A Critical Guide to Erie Railroad v. Tompkins, 54 Wm. & Mary L. Rev. 921, 922 (2013) (quoting Krock, In the Nation: A Momentous Decision of the Supreme Court, N.Y. Times, May 3, 1938, at 22), to “the worst decision of all time.” Sherry, Wrong, Out of Step, and Pernicious:Erie as the Worst Decision of All Time, 39 Pepp. L. Rev. 129 (2011). For an excellent discussion of the decision and the context in which it was decided, see Purcell, The Story of Erie: How Litigants, Lawyers, Judges, Politics, and Social Change Reshape the Law, in Civil Procedure Stories 21 (Clermont ed., 2d ed. 2008).