Examine the extent and limits to which a treaty can confer rights and impose obligations on the third State which is not party to the treaty.

The Theoretical Framework: VCLT and Third States

The Vienna Convention on the Law of Treaties (VCLT) explicitly states in Article 34 that a treaty does not create obligations or confer rights on a third state unless it is intended to do so by the treaty-making states. This establishes the general principle of pacta tertiis non nocent – a treaty does not harm third states. However, this principle is not absolute. Exceptions exist.

Ways a Treaty Can Confer Rights and Impose Obligations on Third States

1. Customary International Law

Treaties, especially those with widespread participation and consistent state practice over time, can contribute to the formation of customary international law. When a treaty's provisions become generally accepted as legal rules binding on all states, including non-parties, it effectively transforms the treaty's content into a rule of customary international law. For instance, the Geneva Conventions on humanitarian law, though initially treaties, have largely become customary international law.

2. *Jus Cogens* Norms

Treaties that codify *jus cogens* norms – peremptory norms of general international law from which no derogation is permitted – bind all states, regardless of treaty participation. These norms are fundamental principles accepted by the international community as a whole. Examples include the prohibition of genocide, slavery, and torture. A treaty provision conflicting with *jus cogens* is void *ab initio* (from the beginning) for all states.

3. Treaty Provisions Intended to Benefit Third States

Treaties can explicitly state their intention to confer rights or impose obligations on third states. This is relatively rare, but it can occur, for example, in treaties establishing international organizations or regulating international waterways.

4. Treaty as Evidence of State Practice and *Opinio Juris*

Treaties provide valuable evidence in determining the existence of customary international law. The widespread ratification and consistent implementation of a treaty provision can be strong indicators of state practice and *opinio juris* (the belief that the practice is legally obligatory), both of which are essential for the formation of customary international law.

Limits to the Impact of Treaties on Third States

1. VCLT's Restrictions

Article 36 of the VCLT explicitly states that a treaty does not create obligations or confer rights on a third state unless the parties to the treaty intend to do so. This is the cornerstone of limiting the treaty’s impact.

2. Absence of Intention

If the treaty-making states did not intend to create rights or obligations for a third state, the third state is not bound. Establishing this intention can be challenging and often involves interpreting the treaty's text and the negotiating history.

3. Conflict with Customary International Law

If a treaty provision conflicts with an existing rule of customary international law, the customary rule generally prevails. Treaties cannot legally override rules of customary international law.

4. Reservations and Interpretations

Reservations made by states when ratifying a treaty can significantly impact its effect on third states. Similarly, interpretations of treaty provisions can be contentious and influence how they apply to non-parties.

Case Studies & Examples

Case/Example	Description	Impact on Third States
UN Convention on the Law of the Sea (UNCLOS)	UNCLOS governs the use of the world’s oceans and resources. Some states not party to UNCLOS have argued that certain provisions related to maritime boundaries are becoming customary international law.	Controversial; some argue UNCLOS principles are customary, while others maintain it only binds parties.
International Criminal Court (ICC) Statute	The ICC Statute establishes the jurisdiction of the ICC to prosecute individuals for genocide, war crimes, crimes against humanity, and crimes of aggression.	States not party to the ICC Statute are not directly bound by its provisions regarding the jurisdiction of the court, but they are generally expected to cooperate with the ICC in investigations and prosecutions.

Contemporary Challenges

The increasing complexity of international relations and the proliferation of treaties pose challenges in determining the extent of their impact on third states. The rise of multilateral environmental agreements, for example, often raises questions about the obligations of states that have not ratified them, especially concerning transboundary environmental harm.

In conclusion, while the general principle of *pacta tertiis non nocent* governs the relationship between treaties and third states, the impact is not absolute. Treaties can, under certain circumstances, create rights and obligations for non-parties, primarily through the development of customary international law and the codification of *jus cogens* norms. However, the Vienna Convention on the Law of Treaties remains the primary framework for limiting this impact, emphasizing the importance of the intention of the treaty-making states. As international law evolves, clarifying the boundaries of this relationship will remain crucial for maintaining a stable and equitable international order.