The Conceptual Challenge to Measuring Ideology

Abstract

The concept of judicial ideology is now central to the global study of judicial behavior, yet there has been surprisingly little progress in determining exactly what the term means. This conceptual lacuna partly explains why developing valid measures of ideology is so difficult, especially across different systems. I develop a broad, cross-national, functional definition of judicial ideology, which I use to synthesize the leading theories of judicial decision-making into two-dimensional space. I then review the broad existing approaches to measuring judicial ideology – vote-counting, proxy, and third-party – and consider the implicit assumptions about the nature of judicial ideology that each makes, as well as their relative strengths and weaknesses in measuring ideology. In doing so, I give special attention to one barely explored method for measuring ideology: using the opinions of legal experts to derive quantitative estimates of ideology. I argue that using such expert-based evaluations – inferring ideology from the statements, opinions, and other conduct of judges – can overcome many of the limitations of existing approaches. Regardless of method used, researchers using existing measures or developing new ones should carefully consider the underlying assumptions behind the measure, and in doing so, make those implicit assumptions explicit.

Keywords: judicial ideology, judicial behavior, measurement