Case concerning military and paramilitary activities in and against Nicaragua Nicaragua v. US

1981 US terminated economic aid to Nicaragua on the ground that it had aided guerrillas in El Salvador, by allowing USSR arms to pass through its ports and territory. Nicaragua claimed that US, contrary to IL, used direct-armed force lying mines in Nicaragua internal waters; and giving assistance to the contras. Nicaragua contended US also violated Treaty of Friendship, Commerce and Navigation and 4 multilateral treaties. Because of the US reservation to its acceptance of jurisdiction under optional clause excluding ‘disputes arising under a multilateral treaty’ On the question of law applicable ‘the court has reached the conclusion that it must refrain from applying the multilateral treaties invoked by Nicaragua in support of its claims, without prejudice either to other treaties or to the other sources of law enumerated in article 38 of the Statute’ The issue in this case was: whether customary rules applied in the relations between two states when rules covering the same ground existed in treaties to which those states were parties. Resolution US claimed that rules of CIL have been ‘subsumed’ (include) and ‘supervened’ [in change from] by those of international treaty law (‘Even if a treaty norm and a customary norm were to have exactly the same content, this would not be a reason for the court to take the view that the operation of a treaty process must necessarily deprive the customary norm of its separate applicability’) UN Charter by no means covers the whole area of regulation of use of force. UN Charter does not ‘subsumes and supervenes (resume et supplante)’ CIL. CIL continues to exist alongside treaty law, the norms retain a separate existence. The existence of identical rules in international treaty law and CIL has been clearly recognized by the Court in North Sea Continental Shelf Cases. Those cases turned to the question whether a rule enshrined in a treaty also existed as CIL, either because the treaty had merely codified the custom, or caused it to ‘crystallize’, or because it had influenced its subsequent adoption. (60.3.b VCLT termination or suspension because the violation by the other party of a provision essentially to the object and purpose) … [Although this is valid] if the two rules in question existed in CIL the failure of the one State to apply the one rule does not justify the other State in declining to apply the other rule. Rules which are identical in treaty law and CIL are also distinguishable by reference to the methods of interpretation and application. What are the rules of CIL applicable to the present dispute? it is axiomatic that the material of CIL is to be looked for primarily in the actual practice and opinio iuris (Continental Shelf Libya/Malta 1985) In the field of customary law, contrary to treaty, the shared view of the parties is not enough to create law. The opinio iuris, subjective element, has to be confirmed by the practice. The practice has not to be perfect, in complete consistency; it is sufficient that the conduct of the States in general be consistent with such rules. Inconsistent conducts must be treated as breaches of the rule, not emergence of new rule. The opinio iuris may be deduced from, inter alia, the attitude of the parties and the attitude of States towards certain GA resolutions, in particular resolution 2625 (XXV) 1970. (115) The US participation even if preponderant or decisive, in the financing, organising, training, supplying and equipping of the contras, the selection of military or paramilitary targets and the planning of the whole of its operations, is still insufficient in itself , for the purpose of attributing to the US the acts committed by the contras.. For this conduct to give rise to legal responsibility of the US, it would in principle have to be proved that that state had effective control of the military or paramilitary operations in the course of which the alleged violations were committed The acts of Nicaragua, assuming them to have been established and imputable to that state, could only have justified proportionate counter-measures by the victim state, not a third State.

(176) … article 51 [self-defence] of the Charter is only meaningful on the basis that there is a “natural” or “inherent” right of self-defence, and it is hard to see how this can be other than of a customary nature…. Moreover the Charter, … does not contain any specific rule whereby self-defence would warrant only measures which are proportional to the armed attack and necessary to respond to it, a rule well established in customary international law. (186) It is not to be expected that in the practice of States the application of the rules in question should have been perfect, in the sense that States should have refrained with complete consistency, from the use of force or from intervention in each other´s internal affairs. The Court does not consider that, for a rule to be established as customary, the corresponding practice must be in absolutely rigorous conformity with the rule. In order to deduce the existence of customary rules, the Court deems it sufficient that the conduct of States should, in general, be consistent with such rules, and that instances of States conduct inconsistent with a given rule should generally be treated as breached of that rule, not as indications of the recognition of a new rule. If a State acts in a way prima facie incompatible with a recognized rule, but defends its conduct by appealing to exceptions or justifications contained within the rule itself, the whether or not the State´s conduct is in fact justifiable on that basis, the significance of that attitude is to confirm rather than to weaken the rule. (193) …it is also clear that it is the State which is the victim of an armed attack which must form and declare the view that it has been so attacked. There is no rule in customary international law permitting another state to exercise the right of collective self-defence on the basis of its own assessment of the situation. Where collective self-defence is invoked, it is to be expected that the State for whose benefit this right is used will have declared itself to be a victim of tan armed attack [Commenting on the incursions from Nicaragua into Costa Rica and Honduras, and the supply of arms to the opposition in El Salvador, and regarding the nature of armed attack, the Court said:] (195) the Court sees no reason to deny that, in customary law, the prohibition of armed attacks may apply to the sending by a state of armed band to the territory of another state, if such an operation, because of its scale and effects, would have been classified as an armed attack rather than as a mere frontier incident had it been carried out by regular armed forces (196) there is no rule permitting the exercise of collective self-defence in the absence of a request by the State which regards itself as the victim of an armed attack [regarding the obligation of reporting self defence action under article 51 UN Charter] (200) the absence of a report may be one of the factors indicating whether the State in question was itself convinced that it was acting in self defence (231) there are however other [vg. No declaration of the victim that it was suffering an attack, no request for help to the USA] considerations which justify the court in finding that neither these incursions nor the alleged supply of arms to the opposition in El Salvador may be relied on as justifying the exercise of the right of collective self-defence [see paragraph 195] (236) the condition sine qua non [armed attack?] required for the exercise of the right of collective self-defence by the United States is not fulfilled in this case (268) While the USA might form its own appraisals of the situation as to respect for human rights in Nicaragua, the use of force should not be the appropriate method to monitor or ensure such respect. With regard to the steps actually taken, the protection of human rights, a strictly humanitarian objective, cannot be compatible with the mining of ports, the destruction of oil installations, or again with the training, arming and equipping of the contras (269) …militarization of Nicaragua which the US deems excessive, …an argument to justify its activities with regard to Nicaragua. It is irrelevant and inappropriate, in the court’s opinion, to pass upon this allegation …since in IL there are no rules, other than such rules as may be accepted by the state concerned, by treaty or otherwise, whereby the level of armaments of a sovereign state can be limited, and this principle is valid for all states without exception (270) having concluded the examination of Nicaragua claims based on CIL, the court turns to claims under 1956 Treaty of friendship. Nicaragua argued that US by its conduct has deprived the treaty of its object and purpose, and emptied of real content. Nicaragua has relied on the existence of a legal obligation of states to refrain from acts which would impede the due performance of any treaty entered into them. Is there a duty of a State not to impede the due performance of a Treaty to which it is a party that is not a duty imposed by the treaty itself. Nicaragua contends that this rule is implicit in pacta sunt servanda. (275) there are certain activities of the US which are such as to undermine the whole spirit of a bilateral agreement directed to sponsoring friendship between the two states. (direct attacks on ports, oil installations etc)