This paper examines the legal nature of the ‘rules of international organizations’ as defined by the International Law Commission in its works on the law of treaties and on international responsibility. Part 1 introduces the debate with an example concerning the nature of UN Security Council anti-terrorism resolutions. Part 2 challenges the four theories of the rules envisaged by scholarship. Part 3 is an attempt to examine the characteristics of the legal system produced by international organizations taking advantage of analytical jurisprudence, developing a theory of their legal nature defined as ‘dual legality’. Part 4 concludes by appraising the effects of the dual legality looking at the law of treaties, international responsibility and invalidity for ultra vires acts.

中文翻译：

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国际组织规则的双重合法性

本文研究了国际法委员会在其关于条约法和国际责任的著作中定义的“国际组织规则”的法律性质。第 1 部分通过一个关于联合国安理会反恐决议性质的例子介绍了辩论。第 2 部分挑战了学术所设想的规则的四种理论。第 3 部分试图检验国际组织利用分析法学产生的法律体系的特征，发展一种将其法律性质定义为“双重合法性”的理论。第 4 部分最后评估了条约法、国际责任和越权行为无效的双重合法性的影响。