Bicameralism, the principle of CONSTITUTIONALISM that requires the legislature to be composed of two chambers (or houses), is a feature of the United States Constitution and of the constitution of every state except Nebraska. Bicameralism is supposed to guarantee deliberation in the exercise of the LEGISLATIVE POWER, by requiring that measures be debated in and approved by two different bodies before becoming law. It is also one of those "auxiliary precautions" by which constitutional democracy is protected from the mischiefs latent in popular self-government.
Bicameralism is not distinctively American; there were bicameral legislatures in the ancient republics of Greece and Rome, and there are bicameral legislatures in most countries of the world today. Bicameralism is found in the constitutions of nondemocratic countries (such as the Soviet Union) as well as of democratic countries. And, despite historical association with disparities of social class, both legislative chambers in democratic countries?emphatically including the United States?are typically chosen in popular elections; in countries where one house is chosen other than by election, that house is significantly less powerful than the elective house. Moreover, although it is the practice of most federal nations (such as Australia, Switzerland, and the Federal Republic of Germany) to reflect the constituent SOVEREIGNTY of the states in one house of the legislature, there are bicameral legislatures in countries where FEDERALISM is unknown.
The American colonists came originally from Britain and were familiar with the BRITISH CONSTITUTION. In Parliament, as the Framers knew it, there were two houses with equal power, reflecting two orders of society: the House of Lords comprising the hereditary aristocracy of England (together with representatives of the Scots nobility and the ecclesiastical hierarchy), and the House of Commons representing the freeholders of the counties and the chartered cities. Seats in the House of Commons were apportioned according to the status of the constituency (five seats per county, two per city), not according to population.
The local lawmaking bodies in the colonies were originally unicameral. Bicameralism was introduced in Massachusetts in 1644, in Maryland in 1650, and (in a unique form) in Pennsylvania in 1682; but in each case the "upper house" was identical with the governor's council, and so performed both legislative...