One of the clearest appeals to international law emerged in connection with Iraq`s invasion of Kuwait in 1990. The Iraqi invasion was a flagrant violation of Kuwaiti sovereignty, and the ensuing Gulf War was a multilateral effort to uphold international law. The growing role of international law is evident in the creation of “no-fly zones” in Iraq by UN Security Council Resolution 688 of April 1991, which served as a legal precedent for a number of initiatives, from Somalia to East Timor. The United States generally respects the laws of other nations, unless there is a law or treaty to the contrary. International law is generally part of U.S. law only for the application of its principles to questions of international rights and obligations. However, international law does not prevent the United States or any other nation from enacting laws governing its own territory. A U.S. state is not a “state” under international law because the Constitution does not give the 50 states the ability to conduct their own foreign relations. In addition, judicial decisions and the teachings of eminent experts in international law can be used as “tools for determining legal rules”. States have long relied on international treaties and other treaties to protect themselves against war. The first important step beyond martial law was the Kellogg Briand Pact, signed in 1928 by 63 countries, which condemned the “use of war to resolve international controversies” and renounced war as a political instrument. However, the conflicts of the 1930s made this agreement obsolete.
Some of the measures taken by the Security Council have implications for international law, for example with regard to peacekeeping missions, ad hoc tribunals, sanctions and resolutions adopted under Chapter VII of the Charter. Under article 13 (b) of the Rome Statute, the Security Council may refer certain situations to the Prosecutor of the International Criminal Court (ICC) if it is established that international crimes (such as genocide, crimes against humanity, war crimes, crimes of aggression) have been committed. Sources of international law include international practice (general State practice accepted as law), treaties and general principles of law recognized by most national legal systems. International law may also be reflected in international comity, practices and customs adopted by States for the purpose of maintaining good relations and mutual recognition, such as the salutation of the flag of a foreign ship or the enforcement of a judgment of a foreign court. It is likely that almost all nations almost always respect almost all the principles of international law and almost all of their obligations. The rules of international law come from two main sources: treaties and customary international law, both of which are created by States. States are bound by the rules to which they have committed themselves – rules to which they have subscribed. “Where does international law come from?” explains how international law works and takes into account the nature of customary international law and treaties. Customary law systems, including customary international law, are based on the regularity of a particular practice, while a treaty is a legally binding agreement between States.
Often, the general principles set out in laws need to be communicated through detailed technical rules and standards. A more recent concept is “supranational law,” which concerns regional agreements where the laws of nation-states can be declared unenforceable if they conflict with a supranational legal system to which the nation is contractually obliged. [9] Supranational legal systems arise when nations explicitly attribute their right to make certain judicial decisions to a common court. [10] The decisions of the Common Court are directly in force in each State Party and take precedence over the decisions of the national courts. [11] The European Union is the most striking example of an international treaty organisation implementing a supranational legal framework, with the European Court of Justice taking precedence over all courts of the Member States in matters of EU law. Despite all this, international law is often respected. This can be attributed in part to the support of the great powers, but much of international law is also based on common practice. International law may be applied by States acting unilaterally when it is in their interest or by multilateral action where there is sufficient consensus. Reciprocity can play a role, as benefits can be gained in other areas through compliance. In addition to ad hoc efforts to enforce international law, a number of formal courts have been established for this purpose.
Customary international law derives from the ongoing practice of States, accompanied by opinio juris, that is, from the conviction of States that consistent practice is required by a legal obligation. Judgments of international tribunals as well as academic articles have traditionally been considered convincing sources usually alongside direct evidence of state conduct. Attempts to codify customary international law gained momentum after the Second World War with the formation of the International Law Commission (ILC) under the auspices of the United Nations. Codified customary law is the binding interpretation of underlying customary law by contractual agreement.