One of the most important sources of international law is the formal treaties formed between or among nations. A bilateral treaty is an international agreement that has a legally binding effect on two sovereign states, while a multilateral treaty is an international agreement that has a legally binding effect on three or more states. (This definition applies even if an international agreement does not include the word “treaty.”) Sometimes a UN organ or another pre-existing international organization oversees treaty negotiations. In other cases, a treaty may be negotiated by an entity formed for that purpose.
Once representatives of the sovereign states negotiating a treaty have signed it, the treaty may become legally binding immediately. However, some treaties provide that they must be ratified by a signatory state to legally bind that state. Ratification involves formally confirming in writing that the state consents to the treaty and depositing the ratification instrument at a place provided by the treaty.
Amendments to Treaties
If a treaty is later amended, the amendment is generally binding only on states that have ratified the amendment. Some treaties do not require ratification of amendments to make them legally binding, though, such as the UN Charter. Resolutions by UN organs are technically considered amendments to the UN Charter, and states that have signed and ratified the UN Charter have agreed to be bound by these resolutions.
Treaties and Executive Agreements Under US Law
An international agreement is defined as a “treaty” under US law only if it has received the advice and consent of two-thirds of the Senate and has been ratified by the President. Both of these steps are essential. If the Senate consents to a treaty, but the President declines to ratify it, the treaty will not take effect for the US. This has happened several times.
On the other hand, sometimes the President negotiates an international agreement but does not get the consent of two-thirds of the Senate. This is known as an executive agreement under US law, but it is still considered a treaty under international law. There is no functional distinction between treaties and executive agreements regarding US obligations under international law. Both types of agreements are legally binding.
Two Types of Executive Agreements
Congressional-executive agreement: receives the approval of a simple majority of both houses of Congress; can be used in the same situations as treaties
Sole executive agreement (presidential agreement): no Congressional involvement; usually limited to situations controlled by Presidential authority as commander-in-chief of the US military and chief diplomat of the US
Treaties and other international agreements take direct legal effect in US courts only if they are implemented by a federal law or if they are considered self-executing. A treaty provision is usually considered self-executing if a court finds an intent to make it enforceable US law without additional legislation to implement it. Relatively specific treaty provisions that resemble federal laws are more likely to be considered self-executing. Each provision in a treaty may be evaluated independently, meaning that some could be considered self-executing but others not. A provision does not need to be self-executing under the laws of other nations that signed the treaty to be considered self-executing under US law.
Sometimes a court does not directly address the question of whether a provision is self-executing. If it enforces a provision not implemented by federal law, this indicates that the provision is self-executing even without an explicit statement to that effect.
The main difference in effect between self-executing and non-self-executing treaties is that only self-executing treaties supersede prior inconsistent federal laws. However, this does not mean that non-self-executing treaties are meaningless. A President cannot violate or disregard a treaty that is consistent with the Bill of Rights, even if it is not self-executing. Moreover, any treaty or international agreement prevails over conflicting state or local laws. This is because the federal government holds exclusive power to manage foreign affairs, and a state or local government cannot cause the federal government to violate international obligations.
Overriding a Treaty
Congress can override a treaty (or congressional-executive agreement), but the treaty remains binding on the US under international law. Unless Congress clearly intended to override the treaty, a court generally will try to harmonize the treaty with the potentially conflicting federal law. This prevents a violation of international law. However, a court would override a treaty or executive agreement as unconstitutional if it violated the Bill of Rights.