Sources of international law can be divided into 2 classifications, the first being official and the second being material sources. Official sources are ones that create what the law is, specifically General concepts of law, Customary Law and the International Treaties.
The international sources of law cannot operate separately; the one needs the other for a strong and meaningful execution of justice. The one source uses the other as safeguard for filling the spaces of international law so none of these sources individually of the others can properly show the international law.
There are international practice areas that are not managed by any of the above 4 sources, such as when it comes to a technological development where the time passed was insufficient for the production of legal guidelines, or as in the event where there are states challenging the production of a law as it will contrast their interests like the handful of nuclear States. It can be argued that the 5 sources of international law show to a big level the base for the development of international legal guidelines however not all the international legal guidelines. Article 38 has been much criticized as insufficient, out of date, or ill-adapted to the conditions of contemporary international laws. Another essential source of International Law is reason. Cases frequently develop for which no precedent may exist, and for which there exists no established concept of implied or specific authorization.
In such cases, those who administer International Law should turn to figuring out by factor the concepts of equality to be used. By thinking about precedents, finding examples, and broadening already accepted concepts, they progress a sensible concept to fit the cases under adjudication. Such choices have concerned make up a body of precedents usually accepted as legitimate.