Studies of state supreme courts recognize the policy-making role of state courts, but often assume the decisions made by each court are independent of all other peer courts. While it is true that courts are independent from each other in the sense that they are not bound by the precedent of their peers, (1) and individual court-level attributes, such as ideology and institutional design, influence decisions and policy, a growing body of literature stresses that political actors, such as legislators, interest groups, and others, are interdependent and make decisions based on the attributes and actions of their peers, as well as individual-level factors. (2) This interconnected framework stresses that interactions between actors are governed not just by individual-level characteristics, but also the similarities and differences of actors. This theoretical approach is incompatible with traditional modeling strategies, which assume observations are independent of each other, and necessitates employing social network analysis that explicitly account for interdependence in statistical models. (3) In this study, we extend both the interdependent assumptions of social network analysis and the policy diffusion literatures to state supreme courts by examining education policy diffusion via court opinions. Importantly, we examine education policy diffusion across three waves from 1974 to 2004, which highlights the changing nature of the state supreme court policy network.
State court decisions play a prominent role in many policy areas. In our federalist system, many policy domains are left predominantly to the states, including such areas as marriage, divorce, and, perhaps most prominently, education. (4) Particularly since San Antonio Independent School District v. Rodriguez, (5) state supreme courts are often the final authority on education finance law. (6) However, while the decisions of state supreme courts are final within their jurisdictions, state high courts often look to the decisions of other courts for guidance. (7) Education finance reform is a matter of policy, and while scholars have long recognized the diffusion of policy between state legislatures, no study has, as of yet, studied the diffusion of policy change through the use of state supreme court citations as a diffusion mechanism.
Traditionally, the literature on state courts holds that judicial decisions are a function of attitudes or policy preferences, constrained by institutional considerations and the separation of powers system inherent in each state. (8) Much of this literature assumes that decisions reached by state courts of last resort are largely independent of other state courts of last resort. (9) Each state court has its own preferences; laws; particular set of institutional constraints; and confronts different governors, publics, and state legislatures in rendering decisions. In addition, legal factors such as precedent within the state, state legislative history, and state constitutional and statutory language also play a role. However, this literature largely assumes that the decisions of one state supreme court are independent of decisions reached by neighboring state supreme courts. (10) We contend that this assumption misses the judicial dialog between state high courts. (11)
A small, but growing, literature finds state supreme courts often turn to each other for citations. This literature contends that state supreme courts look to their peers or other courts for guidance, particularly when dealing with a new area of case law. (12) Specifically, state supreme courts tend to cite their peers that are more professional and have specialized case law. (13) Thus, if a court is deciding a securities case, they may turn to the New York Court of Appeals since that court has developed an extensive specialized case law in that area. (14) While this literature is informative to the present study, it does not speak to the diffusion of policy, only the presence of citations. In this article, we wed this literature to that analyzing state policy change.
The diffusion literature shows state legislatures often adopt policy that has previously been adopted by neighboring states. Recent scholarship on policy diffusion has reached beyond the simple concept of geography by focusing on how states and nations learn from or emulate other states or nations, looking for leadership in a particular policy domain. (15) Emulation does not depend upon neighboring geographic lines but, rather, upon whether or not the policy has been adopted by a similarly situated state or nation and whether or not the policy worked. (16)
In one of the rare instances where diffusion has been modeled for state courts' decisions, no influence was seen on state court decisions predicated on neighboring court decisions or neighboring legislative policy. (17) However, other research finds that geographic proximity does matter to citation patterns. (18) We contend that the lack of significant findings by Roch and Howard (19) may be due to failure to account for the inherent interdependence of citation networks. Diffusion necessarily requires states to be considered in relationship to each other, rather than as independent observations as is typical in most research designs. Recent studies of diffusion note that social network analysis, which treats observations as interdependent, holds great promise for modeling diffusion networks. (20) Drawing upon both previous work on state supreme court citations and legislative diffusion, we evaluate the diffusion of state supreme court education policy.
In this article we examine this citation of precedent in the promulgation of public school finance reform rulings. We do so through the examination of education policy diffusion through three successive waves of education finance reform. Importantly, because changes in education finance have gone through three waves from 1974 to 2004, we contend that the underlying data generation process for the network has changed. This highlights the changing nature of the state supreme court policy network.
THE EVOLVING EDUCATION FINANCE REFORM
Education finance reform litigation is not monolithic; rather it has undergone three distinct waves since the 1970s. (21) Diffusion in each of these waves, we contend, will differ based on the environment imposed by the differing balance of power between federal and state courts, the relative focus of litigation, and the accompanying context in which the decisions occur. We now turn to a discussion of the three waves of this evolving network.
Scholars typically date the start of the first wave of education finance reform to the late 1960s. (22) During this first wave, opponents of unequal financing premised the remedy to inequality through the use of the Equal Protection Clause of the 14th Amendment to the U.S. Constitution. (23) However, in San Antonio Independent School District v. Rodriquez, the U.S. Supreme Court ruled that unequal financing for education did not violate the Equal Protection Clause of the U.S. Constitution. (24) That is, "the Constitution did not prohibit the government from providing different services to children in poor school districts than it did to children in wealthy school districts." (25) This action effectively precluded any further court action at the federal level and ended the first wave of court ordered education finance reform. However, the ruling did not exclude further state court action. (26) The second wave rested primarily on state education clauses and state equal protection clauses. (27) This second wave of cases began following the Rodriguez decision and lasted until 1989. (28) The third wave focused on specific adequacy provisions of state constitutions and continues to the present day. (29)
As of December 2009, forty-four states have experienced some form of state education finance litigation. (30) While the first wave failed to effectuate change in financing reform and some of the early phases of the second wave were also often unsuccessful because they relied on state constitution equal protection clauses, (31) the later part of the second wave and the third wave have been much more successful. (32) In these later efforts, plaintiffs shifted to using state constitutional education clauses. (33) In the second wave of reform, these later equity-based cases were initially premised on state equal protection grounds and then centered on state education articles. (34) These clauses, in conjunction with state equal protection clauses, required states to create and maintain public school systems. (35) In the third wave, litigants have particularly focused on these articles to insist that they require the state to fund an acceptable and adequate education. (36) During this third wave, a significant number of litigants have sued to force the political branches to carry out the specific adequacy mandates of prior court orders. (37) It became more common for courts to find themselves in the position of enforcing their own decisions. (38) During this wave one often sees repeat litigation in a specific state. (39) The same parties that had filed suit in previous cases relitigate the matter to ensure that education in the state meets the mandated definition of "adequacy." (40)
In this article, our focus is the way in which the decisions of one court transmit to other courts as a form of diffusion across the three waves. We now turn to a discussion of both citations between state supreme courts and the diffusion of precedent.
STATE NETWORKING: THE DIFFERENCES IN CITATION AND DIFFUSION
The diffusion literature shows that state and national legislatures look to the adoption of policy in other states and nations as models to emulate. Early literature emphasized geographic proximity; a state or nation would adopt a policy that had been promulgated by a geographically neighboring state or nation...