In 1950, the International Law Commission listed the following sources as evidence of customary international law: treaties, decisions of national and international courts, national legislation, opinions of national legal advisers, diplomatic correspondence and practice of international organizations. [1] In 2018, the Commission adopted conclusions on the Customary International Law Inquiry with comments. [2] The UN General Assembly welcomed the conclusions and encouraged their widest possible dissemination. [3] Whether or not states respond to non-state comments, those responsible for enforcing customary laws of armed conflict must always distinguish between speculation and actual opinio juris. In law, only the understanding by States of their binding legal obligations constitutes an opinio juris and can contribute to the formulation of customary international law. The temptation to accept non-governmental studies and commentaries as expressions of customary law should be avoided when States remained silent and the opinio juris was unclear. It is important to note that the purpose of international tribunals is different from that of States. Its judicial function promotes the settlement of disputes. However, States may seek ambiguity in the law for important reasons, such as diplomatic purposes. When courts are forced to assess claims, they tend to develop stronger and clearer legal formulations than states. And although the legal mechanism of non-alcohol is available to recognize unclear laws, the courts rarely use this instrument.
The courts often give the law a finer point than the States. This may be permissible given their judicial mandate. But their work and conclusions, particularly with regard to customary international law, should be viewed with caution. Notwithstanding Article 38(1)(d), its tasks shall not be of a legislative nature. With regard to the mental element, which is opinio juris, the International Court of Justice has further held on the continental shelf of the North Sea that “the acts in question must not only constitute an established practice, but must also be or be performed in such a way as to demonstrate that the practice is justified by the existence of the rule of law, which it prescribes, becomes mandatory. The States concerned must therefore feel that they are complying with a legal obligation. [16] The Court emphasized the need to demonstrate a “sense of legal obligation” distinct from “acts motivated by considerations of courtesy, convenience or tradition.” [16] This was later confirmed in Nicaragua v. United States of America. [17] Customary international law is an integral part of international law.
Customary international law refers to international obligations arising from established international practices, as opposed to obligations arising from formal written conventions and treaties. Customary international law derives from a general and consistent practice of States, which stems from a sense of legal obligation. Two examples of customary international law are the doctrine of non-refoulement and the granting of immunity to visiting heads of State. Martial law, also known as jus in bello, has long been a matter of customary law before being codified in the Hague Conventions of 1899 and 1907, the Geneva Conventions, and other treaties. However, these conventions do not purport to regulate all legal issues that may arise during the war. Instead, Article 1(2) of Additional Protocol I requires customary international law to govern legal issues relating to armed conflict that are not covered by other agreements. [9] [10] In 1950, the International Law Commission listed as evidence of customary international law: treaties, decisions of national courts and tribunals, national legislation, diplomatic correspondence, opinions of national legal advisers and the practice of international organizations (“Report of the International Law Commission to the General Assembly (Part II): Ways to Make Evidence of Customary International Law More Accessible”, [1950] 2 Y.B. Int`l. L. Comm`n 367, DTA Doc.
A/1316). Despite clear statements about its nature and purpose, the interpretative directive has acquired an outsized influence on how important concepts of direct participation in hostilities are interpreted today. States are largely responsible for the subsequent attention given to the ICRC report and its position as the basis for legal discourse in this area. Although some States commented on the report`s findings, many did not react or only reacted to some of its findings. However, the United States subsequently incorporated its views on several aspects of direct participation into the Department of Defense`s Law of War Manual and, in particular, rejected essential parts of the interpretative guidelines as common law expressions (see here for details). There is no doubt that the State`s silence on customary law can create ambiguity, and this ambiguity can, in turn, lead to speculation about the law. While it may be tempting to accept non-State declarations in favour of firm law, those applying the law must avoid confusing the views of non-State actors with what States consider to be their legal obligations under the customary law of armed conflict. Replacing state opinio juris with non-state assessments in the interpretation of customary international law is not only legally unsound, but can also disrupt the norm-making process in a way that ultimately undermines the law. Ideally, states make clear – for example through official statements or diplomatic exchanges – which practices they consider legally binding. However, declarations of opinio juris of the State are not always present. This lack of opinio juris can lead to uncertainty about the law that non-state actors – including lawyers, humanitarian interest groups and non-governmental organizations – would like to resolve. However, the distinction between non-governmental opinion and authentic opinio juris is crucial to understanding the current state of customary law.
International law includes treaties and customary international law. Customary international law is established by measures taken by States by legal obligation. International law evolves as a result of the evolution of treaty regimes, as well as new and different legal norms that States adopt on the basis of what they consider to be the law governing emerging issues. Customary international law and, in recent years, treaty law have played a central and continuous role in the development of the law of the sea. Recognizing this reality, it has long been a principle of international law that a State must explicitly accept a rule (for example, by signing a treaty) before it can be legally bound by the rule. Customary international law not only interferes with this idea of consent, it does so secretly. [12] Opinio juris occurs when states act because they believe that something is prohibited or compelled to do so under international law. It distinguishes between what a State does out of a legal obligation and what a State does out of regular courtesy or comity. Opinio juris is detected by various means. Most of the convention was drafted in such a way as to reflect the sense of obligation that States already felt among themselves with regard to the law of the sea.
The second source, customary international law, is generally recognized as developing from a general and consistent practice of States, followed by a sense of legal obligation. [1] Accordingly, customary international law consists of two parts: state practice and states` subjective understanding of their legally binding obligations – also known as opinio juris. In the formulation of the ICJ in its judgment on the continental shelf of the North Sea, opinio juris is “the conviction that a practice becomes mandatory by the existence of the rule of law which requires it”. Those responsible for the application of customary law of armed conflict, including judges of international tribunals and legal advisers of States, should pay particular attention to recognizing the limitations of non-governmental reports and commentaries and should endeavour to seek the views of States before commenting on customary rules.
