New Project on cross-citations between Supreme Courts in Europe, by Mathias Siems

Recent years have seen a growing volume of research on citations between courts from different countries (in the following: cross-citations) and other forms of judicial dialogue. For example, books by Elaine Mak and Michal Bobek present key insight using qualitative research methods. As far as quantitative research is concerned, the author of this blog post previously co-authored with Martin Gelter a number of articles that were based on a data collection of cross-citations between ten European supreme courts between 2000 and 2007 (see data and publications here).

This blog post is based on a new project that now extends this quantitative research. The first paper of this project is entitled Asymmetric Cross-citations in Private Law: An Empirical Study of 28 Supreme Courts in the EU (authored by Sabrina D’Andrea, Nikita Divissenko, Maria Fanou, Anna Krisztián, Jaka Kukavica, Nastazja Potocka-Sionek and Mathias Siems). It is available as early view in the Maastricht Journal of European and Comparative Law as well as an EUI working paper.

It aims to fill a gap in the current literature by presenting and analysing cross-citations between the highest domestic courts responsible for matters of private law in the EU from 2000 to 2018. The focus on private law courts has been chosen as many other studies have specifically examined judicial dialogue in matters of constitutional law. For constitutional law, some of this research explores judicial dialogue between courts from different parts of the world (notably the influence of the US Supreme Court). For EU private law, it can also be noted that many topics of private law are at the forefront of legislative and non-legislative measures undertaken in order to create a common market.

Specifically, the paper addresses two main questions: first, to what extent do these judges cite foreign case law in their decisions? Second, what may explain the varying levels of engagement of supreme courts with foreign case law? Cross-citations between these courts form the basis of analysis in this paper, as they present a visible sign of the influence of foreign courts on a particular court. The paper also discusses how the judicial style of some courts causes a reluctance to provide detailed explanations of the court’s reasoning. In addition, it suggests that problems with the ease of access to court decisions may partly be responsible for the limited use of cross-citations.

Overall, the paper identifies and analyses 2,984 cross-citations between these 28 supreme courts. This is interpreted as a mixed result as to the nature and frequency of cross-citations between supreme courts in private law in the EU. Only in few instances, we find a reciprocal relationship between the supreme courts of two countries (e.g. the Czech Republic and Slovakia). More generally an asymmetric picture emerges, particularly as far as the relationship between larger and smaller jurisdictions is concerned. Specifically, this paper provides a taxonomy that distinguishes between the categories of ‘true followers’, ‘true comparatists’, ‘reluctant followers’, ‘reluctant comparatists’ and ‘isolates’. The distinctions between supreme courts that cite mainly one country and those that cite more widely are found to be plausible as the former courts were from countries whose legal system has been strongly influenced by the other country. The distinctions according to the frequency of cross-citations are more difficult to explain. For the cases with many cross-citations, we often find that a common language is a key explanatory factor. By contrast, we do not find that the frequency of cross-citations simply follows the divide between legal families, while we do observe that many of the ‘isolates’ were civil law countries from Central and Eastern Europe. It also seems likely that the general judicial style of some of the supreme courts means that they write fairly short decisions, or else refrain from non-essential citations, with the result that citations of foreign courts do not feature frequently.

These instances of few cross-citations may also partly be due to the limitations of transparency and ease of access of supreme-court decisions which are identified in the latter part of this paper. While most of the supreme courts have made their decisions freely available online, we also identify some gaps as well as practical problems in the search functions of the available databases. This is not only a limitation for gaining valuable comparative information, but also a concern for judicial transparency in general and the function of judicial dialogue for EU integration in particular. In order to remedy this situation, some of the ongoing EU measures, for instance, an EU-wide system of Case Law Identifiers and a common database of case law can be helpful. Yet, it is also clear that a more comprehensive use of cross-citations in the EU will only emerge if judges and lawyers perceive themselves as forming part of a common European legal culture. Thus, while the topic of cross-citations seems to be of a specific nature, understanding its current patterns is also a litmus test for European legal integration.

This paper is part of a wider project that will analyse further details of these 2,984 cross-citations. For example, while the paper presented here discusses the total number of cross-citations per court, future papers will explore possible variations across time and areas of law. Some of these forthcoming papers will also be based on methods of econometrics and network analysis. For example, one of these forthcoming papers (draft version available on request) analyses the cross-citations between the 28 courts as a valued network of 28 nodes with tools of network analysis. Specifically, it examines whether the frequency of cross-citations between the courts is mainly a reflection of legal similarities between countries or whether it is due to other factors. The main finding is that non-legal factors play a decisive role (notably language variables), while it is not found that legal families matter. This challenges the view that law is a largely autonomous subsection of society and that judicial behaviour is mostly independent of the socio-cultural context of a particular country. These future papers, as well as the data underlying this project, will also be made available online on the website of this project.

Posted by Mathias Siems, Professor of Private Law and Market Regulation, European University Institute, Florence, Italy