Subsequent agreements and subsequent practice in relation to the interpretation of treaties

Treaties are agreements between two or more states, international organizations, or other entities that are governed by international law. The interpretation of treaties is essential to their enforcement and implementation. While the text of the treaty is the primary source of interpretation, subsequent agreements and subsequent practice can also provide important guidance.

Subsequent agreements refer to agreements between the parties to the original treaty that are made after the treaty enters into force. These agreements can clarify and modify the original treaty, and they can provide additional context for its interpretation. In some cases, subsequent agreements can even supersede conflicting provisions of the original treaty.

Subsequent practice refers to the conduct of the parties to the treaty after its entry into force. This practice can include the way in which the parties have implemented the treaty, as well as their statements and actions regarding its interpretation. The International Court of Justice has recognized that subsequent practice can be used as evidence of the understanding of the parties regarding the meaning and scope of the treaty.

Both subsequent agreements and subsequent practice can play a role in the interpretation of treaties. However, there are some important limitations to their use. For example, subsequent practice cannot be used to create new treaty obligations where none existed before. Similarly, subsequent agreements cannot modify the fundamental principles of the original treaty or undermine its object and purpose.

In addition to these limitations, there are also some important procedural requirements for using subsequent agreements and subsequent practice in the interpretation of treaties. For example, in order to be relevant, subsequent agreements must be made by the parties to the original treaty and must be related to the interpretation of the treaty. Similarly, in order for subsequent practice to be relevant, it must be consistent over time and must be widely accepted by the parties to the treaty.

In conclusion, while the text of a treaty is the primary source of interpretation, subsequent agreements and subsequent practice can also provide important guidance. By clarifying and modifying the original treaty, subsequent agreements can provide additional context for its interpretation. Similarly, by demonstrating the conduct of the parties after the treaty`s entry into force, subsequent practice can be used as evidence of the parties` understanding of the treaty. However, there are some important limitations and procedural requirements for using subsequent agreements and subsequent practice in the interpretation of treaties. As such, it is important to consider these factors carefully in order to ensure that the interpretation of a treaty is consistent with its object and purpose.