Partisan dealignment and committee power in five Westminster parliaments

What explains the power of parliamentary committees? A large literature on the United States Congress sees strong legislative committees as a consequence of legislators’ incentives to cultivate a personal vote. These incentives are typically understood to be determined by formal electoral rules. How legislatures are elected thus shapes how they are organised. This article argues that explanations of legislative organisation should also consider a non-institutional source of personal vote-seeking incentives: voters’ partisanship. Where partisan dealignment is more extensive, legislators have stronger incentives to develop a personal vote. Where committee systems are more powerful, legislators have better opportunities to do so. Partisan dealignment should thus lead to stronger committee systems. This argument is supported by analysis of original data on the postwar evolution of committee systems in five ‘Westminster’ parliaments. Partisan dealignment is associated with larger committee systems, and with larger expansions of committee systems.