On the Perils of Drawing Inferences about Supreme Court Justices from Their First Few Years of Service
Epstein, Lee, Quinn, Kevin, Martin, Andrew D., Segal, Jeffrey A., Judicature
Even before the start of their second year in office, commentators were already reading the tea leaves on Samuel A. Alito, Jr. and John G. Roberts, Jr. According to the prominent legal scholar Erwin Chemerinsky, the two new justices "were every bit as conservative as conservatives had hoped and progressives had feared. [Their] willingness to overrule decades-old precedents certainly gives a sense that major changes are likely ahead in constitutional law in the years to come.'" Chemerinsky was hardly alone; similar forecasts appeared on the editorial pages of newspapers as ideological disparate as the Wall Street Journal and the New York Times, as well as hundreds, if not thousands, of blogs across the country.
Forecasting of this sort-a veritable cottage industry each time a new justice completes a term or two of service-may seem harmless enough and sufficiently divorced from the concerns of empirical legal studies to ignore. Nonetheless, the entire enterprise rests on a strong empirical assumption, which, in fact, has important implications for systematic scholarship: that one can draw high-quality inferences about the justices' long-term ideological tendencies from their first few terms in office.
Is this a plausible assumption? Unfortunately, and despite decades of study, we cannot offer a conclusive answer. To some, most notably Hagle, reliance on initial voting records to predict future behavior borders on the absurd.2 Most justices, he empirically demonstrated, manifest unstable behavior in their "freshman" year relative to the balance of their career. To other scholars, most recently Shipan, predictions based on the first term are not particularly troubling.3 The instability identified by Hagle, they say, appears insufficiently widespread to be "considered a general phenomenon."4 In between comes work by Wood et al., which found that roughly half the justices under analysis experienced "acclimation" effects.5
In what follows, we hope to bring a fresh eye to this seemingly age-old but nonetheless on-going debate.6 Drawing on methodological strategies that we used to examine ideological drift on the Supreme Court,7 we first contemplate the literature's primary concern: to what extent do new justices evince different or unstable behavior in their first year relative to all others? Or, to frame it in more contemporary terms, to what extent can we reach high-quality inferences about the justices' long-term ideological preferences based on oneyear's-the first-year's-worth of observations?
Finding that Hagle and others in his camp have the better case-all but 4 of the 26 justices we investigated exhibited statistically significant ideological drift from their initial preferences-we turn to questions of substantive importance. Specifically, we demonstrate that movement away from first-year ideal points occasionally manifests itself in consequential doctrinal change-so consequential that a vote in favor of, say, restricting privacy rights or permitting prayer in school in the first term might translate into a vote in opposition before the justice concludes his or her first decade of service. These findings, compatible with our previous work documenting extensive ideological movement on the part of Court members throughout their careers,8 continue to demonstrate that the ideological boxes into which policy makers, scholars, and lawyers place justices at the time of their appointment are not so tightly sealed.
Inferring future behavior
Inferring future behavior from a justice's first few years in office hardly began with John Roberts and Samuel Alito; in fact, the legal historian George L. Haskins supplies compelling evidence that the practice dates nearly as far back as the Court itself.9 Surely, though, the most (in) famous modern-day example came after Harry A. Blackmun's first year of service. The Minneapolis-born Blackmun was so closely aligned with his boyhood friend, the conservative Chief Justice Warren Burger, that commentators of the day tagged him a "Minnesota Twin. …