Borrowing and non-Borrowing among International Courts

Why do some international courts and judges extensively borrow from other international courts while others do not? Answers to this question have important implications for debates on transjudicial communication, the diffusion of international legal norms, and international judicial behavior. Judges may use external sources because they help improve decisions or because it fits their ideological outlook. They may also use them purposively to achieve a desired effect with a particular audience. First, judges may want to influence other courts, creating incentives to engage in reciprocity. Second, judges may consider the effect of external citations on state parties. External citations could lead to costly charges that judges are exceeding their delegated authority. They also have potential benefits as a persuasive tool, especially in interactions with developing democracies. An in-depth analysis of ECtHR citations reveals that while the court is reluctant to formally acknowledge the influence of other courts, external case-law does play a larger role in separate opinions and deliberations. Moreover, judicial ideology shapes the decisions of judges to borrow or not to borrow from other courts. Interestingly, the arguments advanced by judges for and against reliance on external sources are not unlike those used in the US Supreme Court. A preliminary global analysis of cross-court citations confirms that courts whose membership is dominated by emerging democracies and whose decisions have few direct consequences for state parties are much more likely to rely on external sources. The resulting network of courts is not horizontal and not characterized by reciprocal relationships. Instead, there are a few courts who are the sources of most cases cited by others and who rarely use caselaw developed elsewhere.