International law is the agreed-upon set of rules that nations use in their dealings with one another. The collective agreements that comprise international law are not the same as the laws of a country because there is no overriding central authority and means of enforcement.
Because no single world government exists, international law is established mainly through treaties. These are written promises that nations make to each other. They may include only two nations, or they can be multilateral, which means they are agreements between many nations. The Geneva Conventions would fall under the category of a multilateral treaty.
Another method through which international law is established is custom. This refers to general practices that are accepted as law. The Geneva Conventions, when they became signed treaties, turned customs or conventions into written law. General principles of law, or natural law, are acknowledged as other sources of international law.
Enforcement procedures are often written into treaties, but if they are not, there are certain steps that nations generally take in order to enforce international law. For instance, reciprocity occurs when a transgressing country receives the same behavior that it perpetrates on another country. Collective action involves multiple countries agreeing on certain actions to punish a country that infringes international law. This action may include trade restrictions or other economic sanctions. Shaming is the publicizing of the breaking of international laws to cause the infringing nations to desist.
There are four Geneva Conventions which are considered international law. The first was established in 1864 and signed by 12 European countries and kingdoms. The agreement was reviewed in 1906 and 1929, but the contemporary form of the Geneva Conventions, which has four parts, was finalized in 1949 after World War II.
The first convention is intended to protect sick and wounded soldiers, religious and medical personnel, and medical units and transport. The second convention protects sick, wounded, and shipwrecked military personnel at sea; this protection also extends to hospital ships. The third convention has to do with humane treatment of prisoners of war. The fourth convention is intended to protect civilians in wartime.
Because there is no overriding authority or enforcement system, the Geneva Conventions, like other international laws, rely on the agreement and goodwill of the countries that have agreed to them. They are still relevant and still apply in the modern era because they have not been abrogated. However, some countries attempt to use individual interpretations to circumvent them. An example from recent history concerns the Taliban and Al Qaeda prisoners of war held by the United States at Guantanamo Bay. According to President George Bush, these were not prisoners of war but rather "unlawful combatants" and therefore the Geneva Conventions did not apply in their treatment.