A more thorough explanation:

Law between states refers to the legal system that governs the relationships between nations. It is also known as international law or the law of nations. This legal system not only applies to nations but also to international organizations and individuals who invoke their human rights or commit war crimes.

For example, the Geneva Conventions are a set of international laws that govern the treatment of prisoners of war and civilians during armed conflicts. These laws apply to all nations that have ratified the conventions, as well as to individuals who violate them.

Customary international law is another important aspect of law between states. It derives from the practice of states and is accepted by them as legally binding. This is one of the principal sources of the international legal system.

Private international law, also known as international conflict of laws, deals with legal disputes that involve more than one country. For example, if a person from one country sues a person from another country, private international law determines which country's laws apply to the case.

Overall, law between states is a complex legal system that governs the relationships between nations and individuals on an international level.