- international conventions of general or particular nature;
- international custom, as evidence of a general practice accepted as law;
- the general principles of law recognized by civilized nations.
Most international law experts would rush to add the "unilateral acts" to these three sources of law and to declare that Article 38 of the Statute has omitted to mention these unilateral acts which the United Nations' International Law Commission (ILC) currently tries to codify. Contrary to this opinion, other international lawyers would maintain that these unilateral acts constitute specific expressions of the will of States leading eventually to agreements which are then governed by the rules applicable to international conventions.
Finally, the idea of justice and equity originating in the philosophy of natural law is not to be discarded as a source of international law, since it is the opinion of the International Court of Justice itself that whatever the legal argumentation of the judge, his or her decisions have to be just and in that sense must correspond to justice and equity. Moreover, the judges of the International Court of Justice are expressly authorized to decide a case ex aequo et bono, if the parties agree thereto, i.e. to found their judgements on arguments of equity (Article 38 (2) of the Statute of the International Court of Justice).
International treaty law as codified by Vienna Convention on the Law of Treaties of 1969 is open for considerations of justice too (Preambular para. 4 and 5 and Article 44 (3)). Moreover, the concept of "jus cogens" seems also to be an angle of incidence for natural law ideas.
Since, on the basis of their sovereignty and therefore independence, the equality of all States consitutes the theoretical foundation of international relations and although public international law, by definition, does not belong to civil law, international legal debates are often reminiscent of the discussions known in the latter area, in particular in the context of the law of contracts.
However, this cannot be said for those measures which are taken on the basis of Chapter VII of the Charter of the United Nations. Although they are foreseen in an international treaty - in particular by Article 25 of the Charter - these measures deserve to be highlighted because of the legal obligations they impose to the whole world, their political significance and the remarkable development they have undergone since the Gulf War of 1991. The measures taken by the Security Council and which are expressly based on Chapter VII of the Charter encompass
not only military as well as economic sanctions against
- certain States (
- or insurgents (
1173/1998 of
but also
- the creation of special tribunal to prosecute war crimes or crimes against humanity in the territory of the former Yougoslavia (res. 827/1993 of
(res. 955/1994 of
- or of special administrative zones like in
- measures against terrorism in general (res. 1373/2001 of
- judicial decisions (although even the decisions of the International Court of Justice have binding force only between the parties and in respect of the particular cases submitted to the
Court - Article 59 of the Statute) and
- the teachings of the most highly qualified publicists of the various nations.