Divided Politics: Bicameralism, Parties, and Policy in Democratic Legislatures

This article surveys the rationales for and effects of legislative bicameralism. At heart, second chambers facilitate representation for groups or interests that otherwise might be ignored. They do so not only by making more legislative seats available to legislators elected from different districts and possibly by different rules, but more importantly by giving more legislators a voice in the legislative process. Traditional views of bicameralism hold that second chambers can matter because their members have the authority to veto or at least delay bills, so that whether they do in fact affect legislative content depends on whether and to what extent majority preferences differ across chambers. A new current of legislative research focuses on how the existence of a second chamber provides a forum for bargaining over policy and, in the process, creates a need for policy bargains within parties as well as across chamber majorities that would be unnecessary in a unicameral legislature.