[Footnote 9: See Oppenheim, "Die Zukunft des Völkerrechts" (1911), _passim_.]
[Sidenote: External Power for the Enforcement of Rules of International Conduct.]
§ 9. But how do matters stand concerning the third essential condition for the existence of law? Is there a common consent of the community of States that the rules of international conduct shall be enforced by external power? There cannot be the slightest doubt that this question must be affirmatively answered, although there is no central authority to enforce those rules. The heads of the civilised States, their Governments, their Parliaments, and public opinion of the whole of civilised humanity, agree and consent that the body of rules of international conduct which is called the Law of Nations shall be enforced by external power, in contradistinction to rules of international morality and courtesy, which are left to the consideration of the conscience of nations. And in the necessary absence of a central authority for the enforcement of the rules of the Law of Nations, the States have to take the law into their own hands. Self-help and intervention on the part of other States which sympathise with the wronged one are the means by which the rules of the Law of Nations can be[10] and actually are enforced. It is true that these means have many disadvantages, but they are means which have the character of external power. Compared with Municipal Law and the means at disposal for its enforcement, the Law of Nations is certainly the weaker of the two. A law is the stronger, the more guarantees are given that it can and will be enforced. Thus, the law of a State which is governed by an uncorrupt Government and the courts of which are not venal is stronger than the law of a State which has a corrupt Government and venal judges. It is inevitable that the Law of Nations must be a weaker law than Municipal Law, as there is not and cannot be an international Government above the national ones which could enforce the rules of International Law in the same way as a national Government enforces the rules of its Municipal Law. But a weak law is nevertheless still law, and the Law of Nations is by no means so weak a law as it sometimes seems to be.[11]