What Is a Unicameral System?

A unicameral system is a legislature that has a single legislative chamber or house. All lawmaking authority is concentrated in that one body, which debates, amends, and votes on bills without the need for approval from a second chamber.

Key takeaways:
* Unicameralism concentrates legislative power in one chamber, simplifying the process of making law.
* It can increase efficiency and reduce costs but offers fewer institutional checks than a bicameral system.
* Examples include Sweden, Denmark, Hungary, Turkey, and New Zealand. In the United States, Nebraska is the only state with a unicameral legislature.

How a Unicameral Legislature Works

In a unicameral system, elected representatives sit in a single chamber that:
* Introduces and debates bills.
* Refers bills to committees for study and amendment.
* Holds public hearings (in some systems) before votes.
* Passes legislation by majority vote, subject to any constitutional requirements or special voting thresholds.

Example — Sweden:
* The Riksdag is a single chamber of 349 seats.
* Parties that receive at least 4% of the national vote are eligible for seats; allocation uses proportional representation.
* Most ordinary laws pass by simple majority. The Riksdag also approves the prime minister and meets in regular sessions; elections occur every four years.

Advantages

• Faster lawmaking — no second chamber to reconcile conflicting versions.
• Lower cost — fewer legislators and institutional overhead.
• Greater transparency and accountability — a single body is publicly responsible for decisions.
• Simpler procedures — fewer steps for bills to become law, which can reduce gridlock.

Disadvantages

• Fewer institutional checks — less internal review can increase the risk of poorly considered or unpopular laws.
• Greater vulnerability to majority dominance, special interests, or groupthink.
• Reduced representation of diverse interests that might otherwise be reflected in two differently constituted chambers.
• Potentially weaker regional or minority protections if the single chamber is nationally dominated.

History and Notable Examples

• Early U.S. experience: The Articles of Confederation created a single-chamber Congress (1781). At the 1787 Constitutional Convention the Great Compromise led to the current bicameral U.S. Congress (House and Senate).
• U.S. states: Most states use bicameral legislatures; Nebraska switched to a unicameral, nonpartisan legislature in 1937 after reform efforts led by George Norris.
• International changes: Several countries have abolished their upper chambers (for example, New Zealand in the 1950s) or merged houses, while others retained unicameral systems from their founding.
• Subnational examples: Some Australian states and territories use unicameral legislatures (e.g., Queensland, Northern Territory, Australian Capital Territory).

Unicameral vs. Bicameral (and Monocameral)

• Bicameral: Two chambers (commonly an upper and lower house). Intended to provide checks and balances, represent different constituencies (e.g., population vs. regions), and slow legislation for more scrutiny. Can be more deliberative but slower and costlier.
• Unicameral: One chamber, faster decision-making and lower cost, but fewer internal checks.
• Monocameral: A synonym for unicameral; both terms describe a single legislative chamber.

Common Variations and Rules

Unicameral legislatures differ by country or jurisdiction in:
* Electoral system (proportional representation, single-member districts, mixed).
* Voting thresholds and majorities required for ordinary laws versus constitutional or “fundamental” laws.
* Committee structures and public participation in hearings.
* Formal checks from the executive branch, courts, or direct democracy mechanisms (referendums, petitions).

Short FAQs

Q: What is the only U.S. state with a unicameral legislature?
A: Nebraska.

Q: Is unicameralism the same as monocameralism?
A: Yes — the terms are used interchangeably to mean a single legislative chamber.

Conclusion

Unicameral systems centralize lawmaking in one body, offering speed, cost savings, and simpler procedures. They are well suited to smaller states or those prioritizing efficiency. However, because they lack a second chamber’s internal check, unicameral legislatures rely more heavily on electoral accountability, judicial review, public participation, or executive checks to guard against abuses and ensure thorough scrutiny of legislation.