What it actually is

A treaty is a formal written agreement between two or more countries. It sets out promises, rules, or obligations those countries agree to follow under international law.

Treaties can cover many things: trade, defense alliances, arms control, environmental commitments, and more. They are negotiated by the national government and are meant to be binding on the countries that join them.

How it works

In the U.S. system, the president (or the president's representatives) negotiates and signs treaties with other countries. After signature, the Constitution gives the Senate a role of "advice and consent." In practice the Senate votes to approve or reject a treaty; approval requires two-thirds of the Senators present to concur.

After the Senate gives its consent, the president may ratify the treaty, which makes the United States a party under international law. Some treaties require Congress to pass laws to carry out their terms domestically; others are self-executing and may take effect in U.S. law without additional legislation. Not every international agreement follows the treaty route—some are made as executive agreements and do not use the Senate treaty process.

A real example

Countries use treaties for major defense and diplomatic arrangements. The United States is party to multinational defense treaties that commit member countries to collective security. Those kinds of agreements are sent to the Senate for its constitutional role in approval.

Why it matters to you

Treaties shape things you encounter every day: whether goods move easily across borders, whether airlines can fly between countries, or whether international rules protect the environment or public health. They also influence national security and where U.S. forces can operate.

Because treaties involve legal commitments between governments, the Senate's role means these decisions are part of the national political process—not just the president's choice.

Common misunderstandings

A common mistake is thinking a treaty is the same as any law. Treaties are agreements between countries; once ratified they are binding internationally and often have domestic effect, but sometimes Congress must pass laws to implement them.

Another frequent confusion is between treaties and executive agreements. Executive agreements can be made by the president without the Senate treaty process and are widely used for routine or technical international arrangements. The Constitution's two-thirds Senate consent rule applies to treaties.