We live in an age of measurement and quantification which has produced cross-national indicators of concepts like gender equality, war and peace, and gross national happiness, to name just a few. The rule of law (RoL) is no exception and recent years have seen a proliferation of indicators that are the subject of a nascent literature. The literature points out that indicators inherently reduce complex social phenomena to simple measures with a corresponding loss of information but an increase in tractability.

Some of these indicators measure formal institutions, some measure behavior, while others measure beliefs. These differences are not always transparent. Indicators are also subject to various technical problems of aggregation and endogeneity that are not always clear. As one of us has noted, valid, reliable, and unbiased measures of institutional quality are extremely challenging to produce. Objective measures, such as the number of court decisions that go against the government, are difficult to obtain and raise problems of comparison across countries. Survey data, on the other hand, raise concerns about validity and bias. While the general problems with RoL indicators are well documented, there has been limited systematic inquiry into what these indicators actually capture and how they map onto underlying normative concepts.

In this chapter, drawing on our other work, we take up this task and examine four of the most influential RoL indicators. Specifically, we compare the attempts by the World Bank’s World Governance Indicators project (WGI), the Heritage Foundation, Freedom House, and the World Justice Project (WJP) to quantify the RoL. These are not the only RoL indicators, but they are arguably the most prominent. We show that these four indicators build significantly different substantive values into their definitions of the RoL. The WGI’s RoL indicator focuses on the absence of crime, and the security of persons and their property, the Heritage Foundation’s index emphasizes the protection of private property and the absence of corruption, and Freedom House’s indicator focuses primarily on civil liberties and equality. The WJP’s index uses the most comprehensive definition, which combines rights, crime and security, the absence of corruption, civil justice, and numerous other features into a single (multi-dimensional) indicator.

Tom Ginsburg & Mila Versteeg, Rule of Law Measurement, in The Cambridge Companion to the Rule of Law, Cambridge University Press, 494–512 (2021).