Why do many federal countries have bicameral legislatures?

In federal countries, bicameral legislatures are primarily adopted to uphold the principles of federalism by ensuring that subnational entities—such as states, provinces, or cantons—have a formal voice in the national government.12

By providing a second chamber (often called an upper house or Senate), federal systems can protect regional sovereignty against a central government that might otherwise be dominated by a national majority. This structure allows for the representation of these territorial subdivisions, often through equal representation regardless of population size, as seen in the United States or Switzerland. In other federal models, such as Germany, regional representation is allocated based on population, but the chamber still serves to integrate state interests into federal lawmaking.12

Beyond federal representation, bicameralism is also utilized as an application of checks and balances. This dual-chamber structure is intended to encourage deliberation, prevent hasty or ill-considered legislation, and provide a safeguard against the potential excesses of a single-chamber body.2