Did a Switch in Time Save Nine?∗

Franklin Delano Roosevelt’s court-packing plan of 1937 and the “switch in time that saved nine” animate central questions of law, politics, and history. Did Supreme Court Justice Roberts abruptly switch votes in 1937 to avert a showdown with Roosevelt? Scholars disagree vigorously about whether Roberts’s transformation was gradual and anticipated or abrupt and unexpected. Using newly collected data of votes from 1931-1940 terms, we contribute to the historical understanding of this episode by providing the first quantitative evidence of Roberts’s transformation. Applying modern measurement methods, we show that Roberts shifted sharply to the left in the 1936 term. The shift appears sudden and temporary. The duration of Roberts’s shift, however, is in many ways irrelevant, as the long-term transformation of the Court is overwhelmingly attributable to Roosevelt’s appointees. ∗We thank David Abrams, Barry Cushman, Allie Dunworth, Lee Epstein, David Fontana, Tonja Jacobi, Pam Karlan, Mark Kelman, Jim Lindgren, Yair Listokin, Anne Joseph O’Connell, Nick Parrillo, Erica Ross, Jeff Strnad, Emerson Tiller, Neal Ubriani, Steve Van Winkle, Stephen F. Williams, and participants at the Searle Law and Political Economy Colloquium at Northwestern Law School and the annual meeting of the Midwest Political Science Association for helpful comments and conversations, Sam Caporal, Olivia Puerta, and Neal Ubriani for terrific research assistance, Lee Epstein for generously sharing data, and Mark Ramseyer and an anonymous referee for valuable suggestions. The Institute for Quantitative Social Science at Harvard University, Stanford Law School, and the National Science Foundation (grants SES 03-50613, BCS 05-27513, and SES 07-51834) provided research support. †Assistant Professor of Law & Robert E. Paradise Faculty Fellow for Excellence in Teaching and Research, Stanford Law School, 559 Nathan Abbott Way, Stanford, CA 94305; Tel: 650-723-9560; Fax: 650-725-0253; Email: [email protected], URL: http://dho.stanford.edu ‡Professor of Law, UC Berkeley School of Law, 490 Simon #7200, Berkeley, CA 94720-7200. Email: [email protected]