How Much Influence Do Law Clerks Have on the U.S. Supreme Court?

There is an article in the current issue of the DePaul Law Review entitled Law Clerk Influence on Supreme Court Decision Making: An Empirical Assessment.

In it, Todd C. Peppers (Associate Professor of Political Science, Roanoke College) and Christopher Zorn (Professor of Political Science, Pennsylvania State University) describe the results of their empirical study into the potential influence that U.S. Supreme Court law clerks may have on how cases are selected and decided:

"Drawing upon original survey data on the political ideology of 532 former law clerks, we evaluate the extent to which both the Justice’s personal policy preferences and those of his or her law clerks exert an independent influence on the Justice’s votes. While our results are preliminary, they nonetheless support the contention that — over and above 'selection effects' due to Justices choosing like-minded clerks — clerks’ ideological predilections exert an additional, and not insubstantial, influence on the Justices’ decisions on the merits. In Part II, we first present a short overview of the evolution of the rules and norms surrounding the hiring and utilization of law clerks at the United States Supreme Court, paying special attention to the job duties of clerks on the current Supreme Court. Drawing upon principal-agent theory, in Section II.B, we then discuss the dynamics between law clerks and Justices and the conditions that must be present before law clerks can wield influence. Finally, in Parts III, IV, and V, we propose and empirically test a model of Supreme Court decision making that includes the preferences of law clerks as a separate independent variable."

On December 8, 2008, the New York Times discussed the Peppers-Zorn study.