International law is the law, that regulates the relations between states (And other international entities, such as international organizations) .
Origin and legal effect
International law arises either from customary law, international treaties between entities (for example, an agreement between two states) or general principles of law (for example, that special law proceedes the general legal). Because of the absence of any parent body for international legal entities (for example, a World government) to enforce the law, it lives due to the recognition in the individual countries themselves.
International law is divided into peacetime international law, which among other rules contains provisions for the peaceful settlement of disputes, and war international law, which contains the applicable law in war.
International law and the Basic Law
By default international law obliges states and not individuals. However Article 25 of the Basic Law explained the general rules of international law (that are the rules, which are recognized not only by a few international entities) in the federal territory to be applicable.
The general rules of international law shall be an integral part of federal law. They shall take precedence over the laws and directly create rights and duties for the inhabitants of the federal territory.