Parliaments are unicameral or bicameral. In a unicameral parliament all members of parliament sit in the same chamber and vote on major policy decisions. In a bicameral parliament members meet and vote in two separate chambers, usually called the lower house and upper house. The lower house is usually based proportionally on population with each member representing the same number of citizens in each district or region. The upper house varies more broadly in the ways in which members are selected, including inheritance, appointment by various bodies, and direct and indirect elections.
In most bicameral legislatures, the lower chamber predominates. Especially in parliamentary systems, in which the cabinet is responsible for the parliament, ensuring that the cabinet is responsible only to one chamber is critical. Usually, the upper house is able only to delay legislation passed by the lower house. Sometimes the upper house can veto certain types of legislation. In Germany, for instance, the Bundesrat has veto power over legislation that affects the power of the states (the Lander). In Britain the House of Commons is the dominant partner: Ministers and governments emerge from the lower chamber and remain accountable to it.
A majority of the world’s parliaments are unicameral. However, in 2000, 37 percent of the world’s 178 parliaments had two chambers. This proportion has decreased since World War II as several established democracies have abolished their second chamber, and as new, unitary, and postcommunist states have adopted unicameral assembly. On all continents unicameral assemblies are more common than bicameral ones. For the most part bicameral systems may be found in South and North America and Europe. On the contrary, in Africa and Asia bicameral systems are rather unusual.
According to the political scientist Andrew Heywood (1997), the major benefits of bicameralism are:
• Second chambers check the power of first chambers and prevent abuses of majoritarian rule.
• Bicameral assemblies more effectively check the power of the executive, because there are two chambers to expose the failings of government.
• Two-chamber assemblies widen the basis of representation, allowing each house to articulate a different range of interests and respond to different groups of voters.
• Second chambers act as a constitutional safeguard, delaying the passage of controversial legislation and allowing time for discussion and public debate.
The major drawbacks are:
• Unicameral assemblies are more efficient, because the existence of a second chamber can make the legislative process unnecessarily complex and difficult.
• Second chambers often act as a check on democratic rule, particularly when their members are nonelected or indirectly elected.
• Bicameral assemblies are a recipe for institutional conflict in the legislature, as well as government gridlock.
• Second chambers introduce a conservative political bias by upholding existing constitutional arrangements and, sometimes, the interests of social elites.
In terms of authority and political power bicameral legislatures show large variation. The weakest upper chambers are hardly more than retirement posts for politicians of great merit. On the other hand, with respect to political influence the strongest upper chambers are comparable with the lower chamber or the executive power.
