Do newly appointed justices experience acclimation effects upon their ascent to the Supreme Court? We contend that acclimation is a process, as justices' conformation to the doctrine of stare decisis is partly a function of tenure length. We find that precedent conformance is inversely related to tenure, with newcomers following legal precedents at rates significantly greater than more tenured colleagues; however, justices slowly but surely surrender to relatively unfettered judicial power at the Supreme Court, as attitudes increasingly dominate decisionmaking. While votes adhering to precedent are more prevalent for newcomers, all justices are overwhelmingly influenced by their own ideologies, confirming the inability of the legal model to influence or explain this aspect of judicial behavior. Our results also indicate that the proclivity of prior research to specify an express period of acclimation may be flawed. Instead, acclimation is a dynamic process, ever evolving over justices' entire duration of service.
The study of newcomers to institutions has long been a centerpiece of scholarship in political science, including judicial politics where scholars have considered the role of "freshman effects" on Supreme Court justices. In particular, do newly appointed justices undergo a process of acclimation upon their ascent to the Court, where they must educate themselves of appropriate institutional norms and behavioral expectations? Howard (1965) suggested that it is human nature for newcomers to undergo some period of adjustment in which they acclimate themselves to the norms of one of society's most prominent institutions. The possibility that acclimation effects exist has significant intuitive appeal, as the presence of such influence carries broad implications both for the Supreme Court and for scholars who study this institution.
Snyder (1958) is widely credited with initiating the debate on freshman effects in the judiciary She found that newcomer justices tended to align themselves with more moderate "cliques" (237) on the Supreme Court, as novices were less likely to join the more ideologically extreme groups of justices. Notwithstanding, over time justices would gravitate toward one of the more ideological cliques as they grew more accustomed to their position on the bench. Howard's (1965: 474) study of justice Murphy is another seminal work in this area, similarly concluding that a freshman effect was evident: "The early Murphy . . . was a self-conscious freshman, restless over the personal and professional restraints in his new posl. . . . Equivocation, not activism, was his primary trait." Howard generalized beyond this justice's experience, suggesting that the need for newcomer justices to acclimate themselves was the norm.
In the intervening years since Snyder and Howard paved this research trail, a substantial literature has developed concerning the merit of acclimation effects at the Supreme Court. Biographical studies suggest that institutional norms create an acclimation period for new justices (e.g., Brennan 1983; Frankfurter 1957; Freund 1965; Howard 1965). As well, a myriad of behavioral studies has considered the notion that a newcomer effect might influence the justices, including ideological extremism (Hagle 1993), voting fluidity (Hagle and Spaeth 1991), voting patterns (Heck and Hall 1981; Shipan 2000; Sprague 1968; Wood, Keith, Lanier, and Ogundele 1998), opinion writing (Bowen and Scheb 1993; Brenner and Hagle 1996; Hettinger, Lindquist, and Martinek 2003; Maltzman, Spriggs, and Wahlbeck 2000), and general first-term behavior (Melone 1990; Rubin and Melone 1988; Scheb and Ailshie 1985). Yet, as Hagle (1993) pointed out, empirical verification of acclimation effects in the judiciary is mixed. That scholars continue to study newcomers is likely a function of the theoretic appeal that a learning process of acclimation exists within political institutions. Whereas the congressional literature generally has concluded that apprenticeship no longer is applicable to an institution whose novice members often rise from the ranks of state legislatures where norms are analogous to those in Congress (Hibbing 1991; Rohde 1988), the Supreme Court provides an interesting contrast. …