Treaty

A treaty is a binding agreement under international law concluded by subjects of international law, namely states and international organizations. Treaties can be called by many names: treaties, international agreements, protocols, covenants, conventions, exchanges of letters, exchanges of notes, etc.; however all of these are equally treaties, and the rules are the same regardless of what the treaty is called. Treaties can be loosely compared to contracts: both are means of willing parties assuming obligations among themselves, and a party to either that fails to live up to their obligations can be held legally liable for that breach.

Vienna Convention

The 1969 Vienna Convention on the Law of Treaties is the authoritative treaty on the international law of treaties, establishing the procedures by which treaties are adopted, interpreted, and invalidated. It is considered mostly a codification of already existing and binding customary law on treaties, and so aside from some necessary gap-filling and clarification, it is not viewed as a change in existing international law. This means that unlike most treaties, the Vienna Convention could arguably be binding to even non-parties. There is a Vienna Convention on the Law of Treaties between States, and on the Law of Treaties between States and International Organizations or between International Organizations. Most states have ratified these treaties. The Vienna Convention on Succession of States with Respect to Treaties has comparatively few parties. Many states reject its provisions as not adequately reflecting the customary international law on the subject.

The United Nations

The United Nations Charter states that treaties must be registered with the UN to be invoked before it or enforced in its judiciary organ, the International Court of Justice. This was done to prevent the proliferation of secret treaties that occurred in the 19th and 20th century.

The Charter also states that its members' obligations under it outweigh any competing obligations under other treaties.

Bilateral and Multilateral Treaties

A multilateral treaty has several parties, and establishes rights and obligations between each party and every other party. Multilateral treaties are often, but not always, open to any state; others are regional.

Bilateral treaties by contrast are negotiated between a limited number of states, most commonly only two, establishing legal rights and obligations between those two states only. It is possible however for a bilateral treaty to have more than two parties; consider for instance the bilateral treaties between Switzerland and the EU following the Swiss rejection of the EEA agreeement. Each of these treaties has seventeen parties. These however are still bilateral, not multilateral, treaties. The parties are divided into two groups, the Swiss ("on the one part") and the European Community and its member states ("on the other part"). The treaty establishes rights and obligations between the Swiss and the EC and the member states severally; it does not establish any rights and obligations amongst the EC and its member states.

Execution and Implementation

Treaties may be seen as 'self-executing', in that merely becoming a party puts the treaty and all of its obligations in action. Other treaties may be non self-executing and require 'implementing legislation'--a change in the domestic law of a state party that will direct or enable it to fulfill treaty obligations. An example of a treaty requiring such legislation would be one mandating local prosecution by a party for particular crimes. The division between the two is often not clear and is often politicized in disagreements within a government over a treaty, as a non self-executing treaty cannot be acted upon without the proper change in domestic law. If a treaty requires implementing legislation, a state may be in default of its obligations by the failure of its legislature to pass the necessary domestic laws.

Treaties and Peremptory Norms

Under the Vienna Convention, a treaty is null and void if it is in violation of a peremptory norm. These norms, unlike other principles of customary law, are recognized as permitting no violations and so cannot be altered through treaty obligations. These are limited to such universally accepted prohibitions against waging aggressive war, genocide, slavery, torture, and piracy, meaning that no state can legally assume an obligation to commit or permit such acts.

Reservations

Reservations are essentially caveats to a state's acceptance of a treaty. These can be qualifications or denials of specific obligations, or the insistance upon particular interpretations of treaty language. Some treaties may expressly forbid all reservations or just specific ones. Treaties may also expressly authorize certain reservations. Otherwise, reservations may be permitted to the extent that they are not inconsistent with the goal and purpose of the treaty. Though the allowance of reservations means that not all parties to a treaty will be bound under the same precise obligations, states will often nevertheless consent to reservations to gain as many parties to the treaty as possible for the sake of a general goal.

Withdrawal

As obligations in international law are traditionally viewed as arising only from the consent of states, many treaties allow withdrawal. By following a treaty's withdrawal notification procedures, a state is then considered released from its obligations under that treaty. Many treaties expressly forbid withdrawal. Others are silent on the issue, and so if a state's withdrawal is challenged, a determination must be made whether permitting withdrawal is contrary either to the original intent of the parties or to the nature of the treaty. It is also permitted with the consent of all treaty parties. Withdrawal is impliedly forbidden in human rights treaties.

United States law

Article II, Section 2 of the United States Constitution grants power to the President to make treaties with the "advice and consent" of two thirds of the Senate. However, throughout U.S. history, the President has also made "international agreements" through congressional-executive agreements that are ratified with only a majority from both houses of Congress, or sole executive agreements made by the President alone. Though the Constitution does not provide for any alternative procedure, the Supreme Court has considered these agreements equal to treaties under U.S. law, and that any disagreements are a political question for the executive and legislative branches to work out amongst themselves. These distinctions of procedure or terminology also do not affect the binding strength of such agreements under international law.

Though treaties become part of U.S. federal law, Congress can modify or repeal treaties by subsequent legislative action. The most recent changes will be enforced by U.S. courts entirely independently of whether the international community still considers the old treaty obligations binding upon the U.S.

The U.S. is not a party to the Vienna Convention. However, the State Department has nonetheless taken the position that it is still binding, in that the Convention represents established customary law.

The U.S. habitually includes in treaty negotiations the reservation that it will assume no obligations that are in violation of the U.S. Constitution.