Bicameral legislatures are those whose deliberations involve two distinct assemblies. As such, they are relatively modern political institutions that only gained popularity in the eighteenth and nineteenth centuries, despite much earlier origins in the fourteenth-century English parliament. Nonetheless, earlier political institutions share some of the features of more modern bicameral legislatures, and the intellectual debate over the merits of multiple deliberative assemblies is centuries old. In this chapter, we trace the evolution of bicameral institutions and the intellectual justifications that underpin those structures. We do so by following two threads of analysis, what we call the political and efficient dimensions of bicameralism.

We begin with a definition of the political and efficient dimensions of bicameralism, as these two themes surface repeatedly in the text. We proceed via a chronological overview of the institutional evolution of dual deliberative structures in various eras, accompanied by an intellectual history. In Sections 1 through 3, we review the pre-bicameral institutions of ancient Greece and Rome, the development of the first, class-based bicameral legislature in Britain, and the creation of an alternative federal model in the United States. In Sections 4 and 5, we trace the divergent paths of institutional development in Europe that privilege the distinctions between federal and unitary political systems. Finally, we summarize the contemporary debate on bicameralism, which tends to emphasize either the political or the efficient dimension of bicameral legislatures.

THE TWO DIMENSIONS OF BICAMERALISM

Legislation changes the previously established way of doing things. Whether it regulates behavior in a new way or deregulates behavior and permits individual choice, legislation changes the status quo. In bicameral legislatures, the status quo may be modified in two ways.