bicameralism

Bicameralism is a form of legislative organization in which the lawmaking body is divided into two separate chambers. Each chamber has its own procedures, powers, and composition, and laws typically require approval by both houses, though this can vary by jurisdiction. The terms upper house and lower house are conventional labels that often reflect differences in method of selection, age or experience, term length, or constitutional power rather than an intrinsic ranking.

The rationale for bicameralism includes representing different constituencies (for example, geographic regions or social groups), providing checks and balances on legislation, and allowing deliberation and expertise to refine policy before passage. Upper houses are often designed to be more insulated from rapid electoral pressures, with longer terms or indirect or appointment-based selection, while lower houses usually have more direct electoral legitimacy and greater authority over budgetary and initial policy proposals.

Worldwide examples include the United States Congress, which consists of the Senate and the House of Representatives; the Senate has equal state representation, while the House is apportioned by population. The United Kingdom Parliament comprises the House of Commons (elected) and the House of Lords (appointed, with bishops and life peers). Canada has the Senate and the House of Commons. Germany has the Bundestag (elected) and the Bundesrat (representing the Länder).

Pros include checks and balances, protection for regional or minority interests, and deliberate policymaking; cons include potential gridlock, slower response to changing circumstances, and sometimes unequal representation (as in the U.S. Senate) or higher costs.

Some democracies have moved to unicameral legislatures, citing efficiency and clearer accountability; examples include Sweden and New Zealand.