Examining the Rise of Outside Actor Participation in Constitutional Court Decision Making

Outside actors and interest groups have long been known to influence the decision making of the U.S. Supreme Court (Collins 2018, 2008). More recently, this influence has been seen to extend to the larger common law world (Collins and McCarthy 2017). Despite a general tradition in civil law systems of not accepting amicus briefs, the decision-making process in European constitutional courts today regularly involves consideration of the views from outside actors and outside briefs. Yet, unlike the U.S. Supreme Court, many third-party briefs in the constitutional courts do not arrive unsolicited, but instead are produced and submitted at the direction of the court itself. In this paper we investigate the decision to ask outside actors to participate in the process, and the arguments made by these outside actors in the briefs they submit. Using both interviews with constitutional court judges and dataset of outcomes from multiple constitutional courts, we examine the factors that influence the request for briefs, and the arguments made within the briefs themselves. Notably, we examine how constitutional language is used within these briefs. Do outside actors use specific constitutional terminologies? Are some arguments more likely to lead to success? Do successful arguments use particular constitutional language, or constitutionalized language?