When a treaty is ratified by almost every recognized state in the world, the principles of law contained in the treaty can become customary international law. Customary international law applies to all states, whether or not the state has ratified a treaty that enshrines the principle. There is no set number of ratifications needed to transform the principles of a treaty into customary peoples` law, and states and experts often disagree on the principles that have and have not achieved this status. In addition to treaties, there are other less formal international agreements. These include efforts such as the Proliferation Security Initiative (PSI) and the G7 Global Partnership Against the Proliferation of Weapons of Mass Destruction. Although the PSI has a „declaration of prohibition principles“ and the G7 Global Partnership includes several statements by G7 heads of state and government, it also does not have a legally binding document that sets specific obligations and is signed or ratified by member states. In general, multilateral treaties are open to ratification by any state. Some treaties can also be ratified by supranational institutions such as the European Union and other international organisations. Legislation is an international instrument that sets new standards of common law for a large number of states. For example, the Vienna Convention on Treaty Law defines a „treaty“ as „an international agreement concluded in writing between states and governed by international law, whether it appears in a single act or in two or more related acts and regardless of its particular name“ (Article 2, paragraph 1, point a). A treaty is an agreement between sovereign states (countries) and, in some cases, international organizations, which is binding under international law.
An agreement between an Australian state or territory and a foreign government will not be a treaty. An agreement between two or more states will not be a treaty unless those countries consider making it binding under international law. International agreements are formal agreements or commitments between two or more countries. An agreement between two countries is described as „bilateral,“ while an agreement between several countries is „multilateral.“ Countries bound by countries bound by an international convention are generally referred to as „Parties.“ The IHR (2005) is an international agreement between 194 States Parties and the World Health Organization on surveillance, sunshine and response to all events that could pose a threat to international public health.