Define national law and international law. What is the key difference between the two types of law? List several important sources of international law.

National law is the law that pertains to a particular nation. International law is the law that governs relations among nations. The key difference between national law and international law is the fact that national law can be enforced by government authorities, whereas international law is enforced primarily for reasons of courtesy or expediency. Important sources of international law include customs historically observed by nations in their dealings with each other, treaties, international organizations, and conferences.