International Treaties: Effects, Amendments, Withdrawal, Suspension, and Termination

International treaties create legal obligations among states, but these can be modified, suspended, or terminated. © CS Media.

International treaties are formal agreements established between subjects of International Law with the goal of generating legal effects. These instruments seek to establish clear and predictable legal frameworks governing the interactions between countries across a broad spectrum of areas, from trade and security to environmental protection and human rights. Once signed, these agreements are not merely declarative; they trigger a series of mandatory legal effects for the involved parties, who commit to respect and enforce what has been agreed upon. They can be modified, suspended, or even terminated, subject to the conditions and procedures established both in their own text and in the Vienna Convention on the Law of Treaties of 1969 (VCLT/69).

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Effects of a Treaty

Once ratified and entered into force, treaties become part of the applicable law within each State and, as such, bind not only the Executive branch but also the Legislative and Judicial powers. This implies that national legislatures cannot adopt laws that contravene the provisions of a treaty without incurring international liability for the State. Likewise, national courts are obligated to apply treaties and to interpret domestic legislation in a way that is consistent with the State’s international obligations. Ignoring these obligations could result in violations of International Law, exposing the State to international sanctions or retaliations.

Treaties can also create rights and obligations for third parties, that is, for States or entities that are not parties to the treaty. These effects manifest in various ways:

The treaty may establish a de facto situation, such as opening a river or lake to international navigation, which may or may not be recognized by other States.
The treaty can have direct consequences for a third State. For example, treaties that include most-favored-nation clauses can benefit States even if they are not a party to another treaty. This means that if country A signs a preferential trade treaty with country B, it automatically must extend that same preferential treatment to all countries with which it has agreements that include MFN clauses.
The treaty may establish rights for third parties. For instance, treaties open to accession allow States that did not participate in their conclusion process to enter into these agreements.
The treaty may establish obligations for third parties. An example of this is the role of depositary States in the custody and administration of treaties, as well as guarantee systems where third States ensure the execution of a treaty. A particularly relevant case is that of the UN Charter, which imposes obligations related to international peace and security even on States that are not members.

Amendments of a Treaty

Treaty amendments are modifications applied to its text with the objective of expanding, modifying, or eliminating certain rights and obligations established in the original treaty. These changes can be minor, termed amendments, or more substantial, known as revisions or reforms, depending on their impact on the agreement.

Theoretically, there are no limits to amendments, meaning they must follow a process similar to the conclusion of a new treaty, including the potential need for parliamentary authorization. The approval of amendments generally requires the consent of all the State parties or a qualified majority, typically no less than two-thirds of the State parties. This procedure ensures that the modifications reflect a broad consensus, balancing the need for treaty adaptation with legal stability.

According to Article 40 of the VCLT/69, amendments generally only bind States that have agreed to them. States that do not accept the amendment remain bound by the original text of the treaty. Thus, it is possible for two legal regimes to coexist within the same treaty framework: one for the States that have accepted the amendment and another for those that have not.

However, some treaties establish particular procedures for the validity of their amendments, such as the case with the Covenant of the League of Nations and the Charter of the United Nations:

In the League of Nations, all States that rejected amendments were automatically withdrawn from this organization.
In the United Nations, for an amendment to its charter to come into effect, only the approval and ratification by two-thirds of the UN members, including all the permanent members of the Security Council, is required. This means that an individual State cannot reject an amendment if it has already been approved. In fact, that State will be bound by the amendment regardless of its consent, and it cannot even withdraw from the UN because of it.

Withdrawal from a Treaty

The withdrawal from a treaty represents the unilateral decision of a State to retire from an international agreement, freeing itself from its future obligations without incurring international liability. This mechanism, although limited and regulated, constitutes a legal way for a State to adjust its international commitments to changes in its policies, interests, or circumstances.

According to the VCLT/69, as a general rule, withdrawals are not permitted. There are treaties, like the Charter of the United Nations, that do not contemplate the possibility of withdrawal, demonstrating the intention to create enduring obligations among the parties. Other agreements, due to their nature, such as territorial cession treaties, are also immune to withdrawal.

However, the VCLT/69 establishes exceptional situations under which the withdrawal from a treaty is possible:

If the treaty contains explicit provisions that allow withdrawal. For example, the treaties of the European Union did not have the possibility of withdrawal until the Treaty of Lisbon (2007), which introduced this option through its Article 50, which would be invoked by the United Kingdom in 2017.
If it can be demonstrated that the State parties intended to admit the possibility of withdrawal.
If the nature of the treaty depends on specific political circumstances for its execution. For example, military alliance treaties can be denounced even without an explicit clause allowing it. It is worth noting that trade treaties are not included in this exception.
If, in the absence of an explicit provision allowing withdrawal, a State party requests it and all the others accept it.

When withdrawal is permitted, it must be notified either to the other party (in bilateral treaties) or to the depositary of the treaty (in multilateral agreements). Generally, a notice period of at least 12 months is required before the withdrawal takes effect, during which time the State may retract its decision.

The effects of the withdrawal are ex nunc, meaning they do not affect the obligations already fulfilled under the treaty but apply from the moment the withdrawal becomes effective. Moreover, partial withdrawal is only possible if the treaty specifically allows it or if there is an agreement among the parties.

Suspension or Termination of a Treaty

The suspension or termination of a treaty are mechanisms by which an international agreement may cease to be applicable, either temporarily (suspension) or definitively (termination). These processes are also regulated by the VCLT/69 and have ex nunc effects, meaning they are not retroactive.

There are various circumstances under which a treaty may be suspended or terminated:

A treaty may contain clauses specifying its term of validity or the conditions under which it will cease to apply. For example, the termination of a treaty occurs when everything envisaged in it has been executed (operational exhaustion), or when it has come to involve fewer parties than a number pre-established by it — that is, if the treaty says nothing on the matter, the mere reduction in the number of parties does not lead to its termination. Another relevant example are treaties like the Treaty of Paris, which established the European Coal and Steel Community, which had a duration of 50 years and was terminated thereafter.
A treaty can be suspended or terminated if the State parties agree to it — whether unanimously or by a qualified majority.
A treaty can be suspended or terminated as a result of its violation. For such measures to be taken, the violation needs to be substantial — that is, a rejection of the treaty as a whole or a violation that affects a fundamental clause with respect to the purpose or aim of the treaty in question. In bilateral treaties, the State that suffered the violation may take these measures. In multilateral treaties, each non-violating party may take them with respect to the violating State, and all non-violating parties may take them with respect to the violating State or all the States parties. It is important to note that the non-compliance with human rights treaty norms cannot, under any circumstances, lead to their suspension or termination.
A treaty can be suspended or terminated in the case of a profound and unforeseeable change in circumstances. This possibility is known as the rebus sic stantibus clause. According to it, if the circumstances that were essential for a State’s consent to the treaty change, this change can be a reason for the treaty’s denunciation, suspension, or termination. The outbreak of a war, for example, can lead to the termination of bilateral treaties between the belligerents and to the suspension of multilateral treaties that obligate them. However, of course, treaties on human rights, the law of war, or the establishment of territorial limits will never lose their validity in case of armed conflicts. For some authors, the invocation of the rebus sic stantibus clause requires an agreement between the involved parties — that is, it cannot be unilateral.

In line with Article 63 of the VCLT/69, the breaking off of diplomatic or consular relations between States does not affect the rights and obligations from treaties established between them — unless the existence of such relations is indispensable for the application of the treaty in question.

Conclusion

The enactment, amendment, denunciation, suspension, or termination of international treaties is a domain of crucial importance for international relations. The procedures detailed in the VCLT/69 provide a legal framework for regulating these agreements, ensuring that all actions concerning them are carried out in a stable, orderly, and consensual manner. The system established by the VCLT/69 is flexible, as it allows States to effectively respond to changing circumstances and global challenges. In the end, this blend of stability and dynamism is essential for maintaining the relevance of International Law as a means of regulating relations within the community of States.