What Is a Bicameral Legislature and How Does It Work in the U.S.?

A bicameral legislature is a legislative body made up of two (bi) chambers (camera). It differs from a unicameral legislature in which all members belong to and vote in one House. The United Kingdom's system of government includes a bicameral legislature comprising the House of Commons and the House of Lords. Meanwhile, a typical city council in the United States is an example of a unicameral legislature.

Article I of the U.S. Constitution established the legislative branch, which is composed of the U.S. House of Representatives and the Senate. The House of Representatives acts as the "lower house," while the Senate acts as the "upper house" or "upper chamber." However, the lawmaking process can begin in either the House or the Senate.

Why Does the United States Have a Bicameral Legislature?

The Articles of Confederation were created soon after the Declaration of Independence, but the states did not ratify them until 1781. They created a federal government composed of an alliance of states and a unicameral Congress made up of one delegate from each of the 13 colonies.

However, this lawmaking body was weak and had no real authority to govern on a national level. Congress had no power to tax or regulate foreign or interstate commerce. Moreover, no executive branch of government existed at that time with the authority to enforce the laws passed by Congress. There were attempts to strengthen the Articles, but the states did not act, afraid of creating a Congress with more power than the states.

Given the failures of Congress under the Articles of Confederation, the Framers of the U.S. Constitution wanted to create a powerful legislative body as part of the system of checks and balances. However, they, too, feared a single legislative body might be too powerful.

The Framers looked to history, other countries, and the states to address the form Congress would take. Many of the historical republics the Founders studied had bicameral legislatures. Similarly, the United Kingdom had a bicameral parliament. Many states, however, had established unicameral systems after the Revolutionary War.

The Founders considered this and determined that a two-chambered legislature would be advantageous. Two chambers would provide an additional layer of checks and balances within Congress. James Madison noted that bicameralism would create two "different bodies of men who might watch and check each other."

Creation of the Houses of Congress

Once the Framers accepted the bicameral system, the next problem to address was the makeup of the legislative branch. This was very contentious and threatened to deadlock the Constitutional Convention.

The Founders proposed that Congress represent states' interests in the federal government. The interests of the larger states, mainly in the South, were at odds with those of the smaller Northern states. The Founding Fathers debated two different plans at the Convention:

• The Virginia Plan proposed a state's population would correspond to the amount of representation it would have in Congress. This plan favored the larger states, like Virginia and North Carolina.

• The smaller states objected to the Virginia Plan. They proposed the New Jersey Plan, which provided equal representation among the states in a one-chamber legislature.

The delegates ultimately agreed to the Great Compromise. The agreement combined the two plans by creating a bicameral legislature. It provided for representation by population in one house and equal representation in the other.

Today, members of the House of Representatives are apportioned based on the state's population. Specifically, a state receives proportional representation based on its population. The most populous state, California, sends 52 representatives to the House. Smaller states, like Connecticut (five representatives) and Nebraska (three), send fewer representatives. Voters elect their state representatives by popular vote.

The Senate was apportioned based on equal representation for the states. Each state, regardless of size, has two senators. Initially, electors from the state legislature selected senators. However, the appointment of senators caused many problems, including vacant seats and corruption.

The Seventeenth Amendment, ratified in 1913, allows for the popular election of the senators. Today, the Senate has 100 members. In the event of a tie, the Vice President, serving as President of the Senate, will break the tie.

The Legislative Process Under Bicameralism

Only Congress has the power to change existing laws and create new ones. The process of making a law depends on bicameralism. To become law, a bill must pass through both the House of Representatives and the Senate in identical form, which can often take a long time.

A bill's sponsor can introduce it in an appropriate chamber for consideration. After the sponsor introduces the bill, it goes to a specific committee that deals with bills of that kind. For example, suppose a representative introduced a bill that would affect agricultural regulations. In that case, the House Committee on Agriculture would likely discuss and debate it. The committee may make changes or add amendments to the bill.

After the bill passes the committee, it goes to the main body for a vote. If it passes, the chamber will send the bill to the other chamber (either the House or Senate, depending on where the sponsor originally introduced it).

The other chamber may also propose changes or amendments to the bill. If a bill passes one chamber but is amended by the other, the amending chamber must return it to the original one for approval.

Congress, the Executive Branch, and the Separation of Powers

Once both chambers approve a bill, they send it to the executive branch. There, the president may sign it into law or veto it. If they sign it into law, it takes effect immediately. If the president vetoes the bill, the House and Senate may vote to override the veto. If two-thirds of each chamber votes to override the president's veto, the bill becomes law.

Requiring the president to sign the bill into law and allowing Congress to override a veto is an example of the separation of powers essential to the U.S. government.

On the one hand, requiring bicameral chambers to discuss, debate, and approve legislation ensures that any proposed law receives careful study and deliberation.

On the other hand, requiring the executive branch (i.e., the president) to sign off on any legislation protects people from "improvident laws" that Congress may attempt to pass. If the president disagrees with the bill, they may veto it. The president cannot make changes or amendments to the proposed bill.

When the president vetoes a bill, it goes back to Congress. There, the chambers may continue to debate the bill and make changes or amendments. Alternatively, they may take a vote to override the president's veto. If Congress successfully overrides the president's veto, the bill becomes law.

This procedure safeguards against tyranny, either from Congress or the president. It prevents a potentially corrupt Congress from abusing its legislative power and passing "bad" laws. It also stops an authoritarian president from having unfettered power to block legislation from becoming law. This balance is one of many reasons the separation of powers between the branches of government is essential to U.S. governance.

Limited and Enumerated Powers

As an additional way to check Congress's power, the Framers limited their powers to those specifically enumerated in the Constitution. Each chamber has certain separate powers that the other does not.

House of Representatives

The Constitution grants specific powers to the House of Representatives that reflect the idea that the House is "closer" to its constituents than the Senate. This notion comes from the fact that the states have always elected their representatives by popular vote. Theoretically, they are in the best position to understand their constituents' issues.

The powers the Constitution gives to the House reflect this idea. One of the House's powers is control of the metaphorical purse strings. Under the Origination Clause, all bills for raising revenue must start in the House. The Senate may amend these bills, but they must always originate in the House.

Representatives also serve only two-year terms. This means they must always consider what their constituents want and what will get them re-elected. In theory, this provides for better representation.

The House also has the power to impeach the President and other federal officials. Specifically, the House files articles of impeachment, and the Senate will then hold an impeachment trial.

In the event of an Electoral College tie in a presidential election, the House has the power to elect the president. For example, during the 1824 election, no candidate received a majority of the electoral vote. The House held a contingent vote, and John Quincy Adams became president without winning the popular or electoral vote.

Senate

The Senate can confirm the President's appointments that require confirmation. For example, they confirm cabinet members, Supreme Court Justices, and the federal judiciary. However, if the Vice Presidency is vacant, the House of Representatives must also approve the appointment of the Vice President.

The Senate also tries impeachment cases sent by the House. Finally, the Senate provides advice and consent on and ratifies treaties (except those that affect foreign trade, which must also get House approval).

Senators have longer terms than U.S. Representatives. Senators serve for six years instead of two before having to seek re-election.

Effect on Other Countries

Bicameralism created a powerful Congress in the United States. It serves as an additional layer of checks and balances. Other countries have set up bicameral legislatures based on the English and American models, creating large "first chambers" like the House of Representatives and smaller "second chambers" like the Senate.

A bicameral model is often used in countries with a national legislature, known in the U.S., Canada, and Australia as the federal legislature. Denmark employed a bicameral legislature for around a hundred years before switching to a single-chamber model in 1953. Some countries refer to their legislative systems as "parliamentary systems."