International Treaties: Definition, Synonyms, and Types

International treaties tend to be of various types, but all are considered mandatory for subjects of law. © CS Media.

An international treaty is a formal agreement established between subjects of International Law with the aim of producing legal effects. That being said, there are many terms used by experts to refer to treaties, such as ”agreement”, “statute”, “convention”, and “concordat”. Each of these has a specialized meaning. Moreover, there are some concepts that refer to documents that are not treaties, such as “gentlemen’s agreement” or “memorandum of understanding”. Distinguishing between these terms is crucial for understanding and appropriately applying International Law.

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Definition of International Treaty

An international treaty is defined as a formal agreement established between subjects of International Law aimed at producing legal effects. This definition is important because it helps understand the elements of a treaty: its formality, the parties involved, and its legal consequences.

Treaties, by their nature, are formal agreements. This formality is expressed in the requirement that the parties involved explicitly express their will to be bound by the agreement. This aspect is fundamental, as it ensures that all participants have a clear and unanimous understanding of the commitment undertaken. In the legal field, especially according to international custom, it is emphasized that the expression of a State’s will regarding the content of a treaty must be in writing. However, it’s important to note that within International Law, there are exceptions to this rule. Some treaties may not be written, such as oral treaties. While recognized by international entities like the UN International Law Commission, this modality is usually an exception and not the norm.

Furthermore, only subjects of International Law are empowered to enter into treaties. These subjects are any person or entity that can hold rights and assume obligations within the context of the international legal order. They have the right to participate in treaty-making. However, it is crucial to understand that not all subjects of International Law possess this right. For example, individuals, despite being recognized in certain contexts within International Law, generally do not have the capacity to enter into treaties on their own.

Finally, an international treaty is an instrument intended to produce legal effects. In other words, its reason for being is to produce new norms — rights or obligations — within the international legal system. For an agreement to be considered a treaty, there must be an explicit intention of the parties to be legally bound, known as animus contrahendi, or the intent to contract. This term refers to the real will of the parties to assume obligations through the agreement.

Synonyms for International Treaty

In the realm of International Law, a variety of terms are used to refer to the legal instruments that States and other legal subjects use to regulate their relations. Although commonly grouped under the generic term “international treaty”, these terms have specific meanings and applications that reflect the nature and purpose of each agreement. It is also important to emphasize that some of these terms do not strictly refer to international treaties in a technical and legal sense.

These are some words that normally allude to treaties:

Agreement: Generally used to refer to an act of lesser significance or that involves few participants. Its flexibility allows it to adapt to various international situations.
Charter or Constitution: This term applies to the foundational acts of international organizations, outlining their structure and functions.
Statute: Refers to the legal instrument that establishes and regulates international courts, defining their jurisdiction and procedures.
Commitment: An act through which parties submit a dispute to arbitration, specifying the conditions and terms of the process.
Concordat: Refers to treaties made between the Holy See and other parties on religious matters or the organization of the Church.
Convention: Identifies a multilateral act intended to create norms of general application, often with numerous signatories.
Agreement: Used for cooperation agreements on specific and diverse topics, which can be bilateral or multilateral.
Modus Vivendi: Refers to a temporary arrangement aimed at maintaining the status quo or establishing bases for future negotiations.
Pactum de Negotiando: An obligation to enter into negotiations to conclude a treaty on a specific matter.
Pactum de Contrahendo: A firm commitment to conclude a final agreement on a certain matter.
Protocol: Can refer to the proceedings of a conference or to the norms and decisions emanating from it.

On the other hand, these are some words that do not refer to treaties:

Gentlemen’s Agreement: An informal agreement based on the honorability among statesmen, which, though reflecting serious intentions, do not create legal obligations in the realm of International Law.

Declaration: An act that enshrines principles, often of an ethical or political nature, without necessarily creating legally binding obligations.
Memorandum of Understanding: Although concluded between subjects of International Law, this legal instrument lacks the necessary animus contrahendi to be considered a treaty, since it primarily contains political exhortations without legal obligatoriness.

The distinction between these terms is fundamental for the proper understanding and application of International Law. To identify whether an instrument is or is not a treaty, it is crucial not to limit oneself to the analysis of its name or subject matter, but to examine its production process and its final form — that is, whether the instrument was created by international subjects, mainly by States, with the intention of producing concrete legal effects.

Types of International Treaties

International treaties can be classified in various ways according to their characteristics, objectives, and scope. Below are the main classifications existing in the legal and political sphere:

Bilateral treaties involve only two parties, and multilateral treaties include three or more parties. A very important example of a multilateral treaty is the Charter of the United Nations, which has been ratified by 193 countries to date.
Open treaties allow other States or entities to join the treaty after it has been concluded, and closed treaties do not allow the incorporation of new parties once the treaty has been concluded — except with the authorization of all the parties.
Treaties with a short procedure require fewer formalities for their entry into force — only the signature or endorsement by a representative of an International Law subject, and treaties with a long procedure require more complex processes for entering into force, often requiring ratification after confirmation by national parliaments.
Transitory treaties are those that have an immediate effect but create a situation that persists over time, like boundary treaties, and permanent treaties are those whose compliance and effects extend over time, as is the case with trade treaties and human rights treaties — both generally do not expire.
Restricted effect treaties are those whose effects and obligations apply only to the signing parties, and non-restricted effect treaties are those whose effects may extend beyond the signing parties, influencing other subjects of International Law.

The Vienna Conventions on Treaties

In International Law, there are two fundamental pillars in the regulation regarding treaties, the Vienna Conventions of 1969 and 1986. These conventions establish the rules governing the definition, creation, interpretation, implementation, modification, and termination of treaties.

The Vienna Convention on the Law of Treaties of 1969 (VCLT/69) came into effect in 1980. It focuses exclusively on treaties concluded between States, providing a formal and comprehensive definition of what constitutes such a document. According to this convention, a treaty is “an international agreement concluded in writing between States and governed by International Law, whether embodied in a single instrument or in two or more related instruments and regardless of its particular designation”. According to Article 5 of the VCLT/69, it applies to any treaty that is an instrument constituting an international organization and to any treaty adopted within the framework of an international organization, without prejudice to any relevant rules of the organization.

The Vienna Convention on the Law of Treaties between States and International Organizations or between International Organizations of 1986 (VCLT/86) was intended to govern treaties that are not only concluded between States. This convention is significant because it recognizes the growing importance of international organizations in international relations and the need to regulate the treaties in which these entities participate. However, despite its relevance, the VCLT/86 has not yet entered into force due to not having reached the minimum number of ratifications needed for this. Nevertheless, the rules it contains are currently included in customary international law — that is, the body of unwritten international norms.

Conclusion

International treaties represent a cornerstone in the structure of International Law, serving as essential means for regulating relations between legal subjects at a global level. The diversity of terms used to refer to these agreements highlights the complexity and richness of the international legal sphere. It is essential to distinguish between different types of treaties and related documents, to ensure greater accuracy in the negotiation and implementation of agreements, as well as in the resolution of disputes regarding international rights and obligations. Additionally, it is important to be familiar with the Vienna Conventions on Treaties, of 1969 and 1986, since they contain the main international rules on treaties, their creation, modification, implementation, and termination.