In questions regarding the jurisdiction of the court, the ICJ has the power to determine whether it has jurisdiction over a dispute or not even where the parties think otherwise. A state may consent directly or indirectly to the ICJ’s jurisdiction. Direct consent to the jurisdiction of the ICJ may come by way of declaration whereas indirect consent may be derived from a bilateral agreement which vests jurisdiction on the ICJ or a treaty where a state is a party and the treaty adopts compulsory jurisdiction of the ICJ. For example, in Mexico v. United States of America, the ICJ assumed jurisdiction, despite the withdrawal of the US from the court’s compulsory jurisdiction in 1986. The ICJ assumed jurisdiction simply because ‘Article I of the Optional Protocol concerning the Compulsory Settlement of Disputes, which accompanied the Vienna Convention on Consular Relations’ vested jurisdiction on the ICJ.