|Article 3(3) and Article 4(2) of the Convention allow all watercourse states to become party to an agreement that only refers to a portion of the basin or to a specific project or use if they may be affected by such an agreement. In addition, these agreements cannot adversely affect, to a significant extent,153 the use of the resource by non-participating riparians without their express consent (Article 3(4)). Furthermore, nothing in such an agreement will affect the rights or obligations of non-contracting parties under the Convention. In other words, these provisions safeguard the rights of states that are not parties to partial agreements, but are parties to the Convention (Article 3 (6)). Article 3(6) therefore upholds Article 34 of the Vienna Convention on the Law of Treaties containing the general rule regarding third states – that a treaty does not create either obligations or rights for a third state without its consent.154
153 See Section 3.1.3 for an explanation of significant adverse effects.
154 Vienna Convention on the Law of Treaties, UN Doc A/Conf.39/27 Art 34.
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