Judicial Autonomy Safeguards in Europe: Introducing a New Measurement Tool

Existing scholarship advances two major claims regarding the ex ante and ex post effects of judicial autonomy on the democratic process. First, judicial autonomy is widely regarded as a precondition for the emergence of democracy, insofar as autonomous courts enable credible commitment, constrain executive arbitrariness, and underpin the rule of law (North, Wallis, and Weingast 2009; Carothers 2007). Second, more recent work argues that judicial autonomy is equally crucial for sustaining democracy under conditions of democratic erosion, particularly in the face of populist or authoritarian-leaning incumbents seeking to undermine institutional checks on executive power (Levitsky and Ziblatt 2018; Przeworski 2019). This paper introduces the Judicial Autonomy Index (JAI), a new measurement instrument designed to allow both claims to be systematically tested. Based on a comprehensive longitudinal dataset comprising more than 110,000 data points from 40 European countries over the period 2000-2022, the development and the de jure quality of rule of law safeguards is analysed and assessed in a cross-national and in-case comparative way. The paper introduces the JAI, which – in contrast to existing cross-national measures of judicial autonomy – provides disaggregated and court-sensitive data. It distinguishes between ordinary courts (first-instance, appeal, and highest courts) and apex courts, capturing the fact that judicial autonomy safeguards are often designed, implemented, and contested differently across these institutional arenas. For both court types, JAI measures four core dimensions of judicial autonomy safeguards: selection procedures, institutional self-administration, judges’ rights, and judges’ obligations. Each dimension is further disaggregated into theoretically grounded indicators and fine-grained questions that capture the legal and institutional frameworks governing judicial autonomy. Thus, JAI opens new research avenues by enabling scholars to move beyond the question of whether judicial autonomy is necessary for democracy, toward identifying which safeguards matter most, under what conditions, and in combination with which other constraints on executive power.