Controlling for District Court Judges' Preferences*

Article excerpt

This study invokes the common space scores of executives and senators to generate a number of alternative preference point positions for U.S. District Court judges. Tests of these continuous measures against a null case fact specification suggest that the legal model always proves an effective predictor of decisions, but that ideological influences have incrementally grown throughout the last century. Continuous preference measures that assume a traditional norm of senatorial courtesy tend to be robust in limited samples of more recent outcomes. However, measures that account for cyclical changes in interbranch appointment relationships are more effective for temporally lengthy large N samples. The magnitude of these ideological effects is modest, but not unsubstantial. During the recent era of independent executive-vetting practices, the likelihood of a conservative decision is approximately 78 to 85 percent for Democratic appointees, and 85 to 90 percent for Republican appointees.

The adoption of continuous representations of judges' ideological preferences is an empirical issue that increasingly crosses disciplinary boundaries, including those that exist between political science, criminology, sociology, and the legal academy. The transmission of knowledge and best practices among these fields often stems from methodological critiques, with Epstein and King's "The Rules of Inference" (2002a) acting as an exemplar. At the heart of Epstein and King's (2002a:87) assessment of empirical legal research is the question of how best to control for the ideological preferences of judges and justices. Because this topic is central to the long-standing debate over theories of judicial decision making, such as the legal, attitudinal (Segal and Spaeth, 2002), and strategic (Epstein and Knight, 1998) models, it understandably evoked a fervent discourse - immediate reactions included Cross, Heise, and Sisk (2002), Goldsmith and Vermeule (2002), Revesz (2002), Epstein and King's own response (2002b), and more recently Sisk and Heise (2005). Of these, Revesz (2002:180) and Sisk and Heise (2005) most directly address the issue of preference measurement with a respective focus on the lack of measures and the magnitude of ideological influence.1 Thus, in current context, it seems that this debate no longer centers upon whether ideological preferences in fact matter, but rather how much more they contribute over traditional legal explanations.

The development and incorporation of valid, exogenous, and continuous measures of judges' preferences potentially allows socio-Iegal scholars to make inroads on this important question. Epstein and King (2002a) clearly advocate the use of such measures, which over time have become widely available. At the Supreme Court level, Segal and Cover (1989), Bailey and Chang (2001), and Martin and Quinn (2002) offer competing ideal-point estimates. Giles, Hettinger, and Peppers (2001) have generated continuous representations of U.S. Court of Appeals judges' preferences that are based upon Poole and Rosenthal's (1997) common space scores. Those interested in state supreme courts can take advantage of Brace, Langer, and Hall's (2000) partyadjusted measures.

An obvious gap in alternatives to dichotomous controls for judges' ideology can be found for those courts that are primarily concerned with matters of original jurisdiction (e.g., U.S. District Courts), where one reasonably can hypothesize that case facts and precedents should predominate and that the effects of ideology should be limited in scope.2 A skeptic might point out that a lack of continuous measures at this level merely reflects the weakness of attitudinal explanations within the vast majority of cases heard by American courts. This does not entirely appear to be the case, since studies of U.S. District Court decision making (Carp and Rowland, 1983; Rowland and Carp, 1996) provide an array of evidence supporting ideological influence. …