Michael Cutrone Dept. of Politics Princeton University Nolan McCarty Woodrow Wilson School Princeton University
1. Introduction Perhaps the most conspicuous variation in modern legislatures concerns the practice of granting legislative authority to two separate chambers with distinct memberships. While the majority of national governments empower but a single chamber, at least a third of national legislatures practice some form of bicameralism as do 49 of the 50 American state governments.1 Scholars have made a number of arguments to explain the emergence of bicameral legislatures. One of the most common arguments for the emergence of bicameralism in Britain and its American colonies is that it helped to preserve “mixed governments,” to ensure that upper class elements of society were protected (Wood 1969, Tsebelis and Money 1997). In such settings, bicameralism allowed the upper chamber, dominated by aristocrats, to have a veto on policy. More generally, an explicit role of some bicameral systems has been the protection of some minority who is overrepresented in the upper chamber. A second rationale for bicameralism is the preservation of federalism. The United States, Germany, and other federal systems use a bicameral system in order to ensure the representation of the interests of individual states and provinces, as well as the population
Tsebelis and Money (1997, 15) define bicameral legislatures as “those whose deliberations involve two distinct assemblies.” This definition, however, masks considerable variation in the roles of each chamber in policymaking. Many “upper” chambers have legislative prerogatives that are limited in important ways; for instance, the British House of Lords is unable to originate monetary legislation and, at best, can delay bills for a year rather than permanently veto those they disagree with. For our purposes, we wish to define bicameralism more narrowly. We define bicameralism as the requirement of concurrent majority support from distinct assemblies for new legislation. It is important to note that our definition treats concurrent majorities as a necessary, but not sufficient, condition for enacting legislation. Thus, it does not preclude other legislative procedures or constitutional requirements, such as the signature of the executive or supermajoritarianism within one of the chambers. Our definition does not map cleanly onto Lijphart’s (1984) distinction between strong and weak bicameralism. His dichotomy classifies systems where both chambers have similar constituent bases as weak even if they required concurrent majorities.
of the country. Under “federal bicameralism”, the lower house is typically apportioned on the basis of population, while the upper house is divided amongst the regional units. Some countries, such as the United States, provide equal representation for the states regardless of their population or geographic size, while others, like the Federal Republic of Germany, unequally apportion the upper chamber by providing additional representation to the larger units. However, despite its prominence, the role of bicameralism in contemporary legislatures has not received the scholarly attention that other legislative institutions have. In this essay, we review and analyze many of the arguments made on behalf of bicameralism using the tools of modern legislative analysis -- the spatial model, multilateral bargaining theory, and games of incomplete information.2 Importantly, this analytical approach allows us to distinguish the effects of bicameralism from those of the institutional features which are often packaged with it, such as supermajoritarian requirements, differing terms of office, and malapportionment. We also review existing evidence of bicameralism’s effect on policymaking.
2. Spatial Models of Policymaking The spatial model of policymaking has become the workhorse model in the study of legislative institutions....