The two essential elements of customary international law are State practice and opinio juris, as confirmed by the International Court of Justice in the legality of the threat or use of nuclear weapons.  In Indonesia, the customary laws of the country`s various indigenous ethnic groups are recognized and the settlement of usual disputes is recognized in Papua. Indonesian Adat legislation is mainly divided into 19 circles: Aceh, Gayo, Alas and Batak, Minangkabau, South Sumatra, the Malay regions, Bangka and Belitung, Kalimantan, Minahasa, Gorontalo, Toraja, South Sulawesi, Ternate, the Mollukks, Papua, Timor, Bali and Lombok, Central and East Java, including the island of Madura, Sunda and the Javanese monarchies, including the Sultanate of Yogyakarta. Surakarta Sunanate and the princely states of Pakualaman and Mangkunegaran. In international law, customary law refers to the law of nations or to the legal norms that have developed over time through the usual exchanges between States, whether on the basis of diplomacy or aggression. In essence, it is assumed that there will be legal obligations between States to carry out their affairs in accordance with conduct accepted in the past. These customs may also change due to the adoption or rejection of certain laws by states. Some principles of customary law have attained the force of peremptory norms that can only be violated or modified by a norm of comparable force. These norms are supposed to draw their strength from universal acceptance, such as the prohibitions of genocide and slavery. The law of international usage can be distinguished from contract law, which consists of explicit agreements between nations to assume obligations. However, many contracts are attempts to codify existing customary law. How does a rule become the law of international usage? Unlike contract law, international usage law is limited in that it is not codified in a clear and accessible format and the content of the rules is generally less specific than what you can find in a treaty. However, as the source of the HVR, customary international law in armed conflict is fundamental, since internal conflicts are protected only to a limited extent by contract law and important treaties are not ratified.
International law exists independently of contract law, and in 2006 the Independent Commission of the Red Cross (ICRC) published a compendium of DRC rules, which are considered customary. They identified 161 rules of international law. Martial law, also known as jus in bello, has long been a matter of customary law before being codified in the 1899 and 1907 Hague Conventions, the Geneva Conventions and other treaties. . . .