The principle of pacta sunt servanda in the practice of International Law

By Ricardo Olvera

The principle of pacta sunt servanda, which in Latin means “agreements must be complied with”, is one of the fundamental pillars of International Law. It establishes the obligation of States to comply in good faith with the international treaties and commitments they have entered into. This principle is enshrined in Article 26 of the 1969 Vienna Convention on the Law of Treaties, the central instrument for the codification of international treaty law.

In practice, this principle is essential to ensure legal stability, the predictability of international relations and cooperation between States. However, its application may be challenged by conflicts of national interests, internal political changes or exceptional situations such as health emergencies or wars.

Scope of the principle in multilateral treaties

Compliance with multilateral treaties such as the T-MEC, the Paris Agreement or the Convention against Torture is directly linked to this principle. When a State party fails to comply with an international obligation, it may give rise to the State’s international responsibility and the activation of dispute settlement mechanisms.

A recent example is the dispute under the T-MEC over the imposition of trade barriers that could contravene the provisions of the agreement. In these cases, the principle of pacta sunt servanda serves as a basis for enforcing compliance and supporting legal claims.

Exceptions and limits to performance

Although the principle requires performance in good faith, international law recognizes exceptional circumstances that may justify non-performance, such as impossibility of performance, fundamental change of circumstances (rebus sic stantibus), or self-defense.

However, these exceptions are limited by strict criteria and must be interpreted restrictively to avoid their abuse. The International Court of Justice and arbitral tribunals have reiterated that pacta sunt servanda cannot be overridden for political or economic expediency.

Implications for Mexico and legal recommendations

Mexico, as a State party to multiple international treaties, is obliged to respect and comply with the commitments undertaken. This includes human rights, trade, environmental and international cooperation treaties. Ignorance or non-compliance with these commitments could generate legal and political consequences at the international level.

ECIJA recommends companies, authorities and individuals operating under international frameworks to periodically verify compliance with their obligations under existing treaties, and in case of disputes, to analyze the diplomatic and legal channels available for their peaceful resolution.

International Area ECIJA Mexico

socios.mexico@ecija.com

(+52 55) 56 62 68 40

www.ecija.com