Origin, Changes and Consequences of Policy Expertise

The literature on legislative activity often relies on the concept of policy expertise. Yet while these studies employ expertise as an explanatory variable, we do not know much about the origins of policy expertise among legislators. In this paper we therefore investigate the origin of and changes in legislators self-declared policy expertise and gauge their impact on a variety of legislative activities. Using observational, census and survey data on 1,676 candidates and Members of Parliament in Japan, we can show that self-declared policy expertise is largely a function of occupational experiences and, for incumbents, previous committee membership. We further find that self-declared expertise nonetheless predicts legislative behavior better or at least as good as ascriptive expertise inferred from occupational backgrounds. Our findings shed light on the prevaling tendency to ascribe expertise based on committee membership and bear implications for the informational theory of committees.