Ideological Drift Among Supreme Court Justices: Who, When, and How Important?

By Lee Epstein, Andrew D. Martin, Kevin M. Quinn, and Jeffrey A. Segal      

[Editor's Note:  This piece is the first in a multi-part dialogue concerning ideological drift on the Supreme Court.  Linda Greenhouse's response can be found here, Stephan Burbank's response is here, and Ward Farnsworth's response is here.]        

I. Introduction

When the U.S. Supreme Court invalidated the Bush administration’s plan to use military commissions to try enemy combatants in Hamdan  v. Rumsfeld,[1] the decision fueled more than a national debate over the powers of the President.  It also generated commentary about the ideological composition of the Court.  Conservatives proclaimed that they were just one Justice, just one vacancy, away from victory in Hamdan[2] and a handful of other recent decisions that worked against their interests.[3]  Liberals worried about just as much.[4]