National law is a set of rules and regulations that exist within the legal framework of a particular nation or state. National laws can come from several sources including legislation passed by legislative bodies, court decisions based on case law and regulations enacted by executive agencies based on statutes. National laws can also be derived from unwritten customary law and trade usages.

National laws are enforceable by governmental bodies, whereas international law has no such enforcement mechanism. In addition, national laws typically cover all citizens of a country while international law only pertains to people who live in or are visiting a particular nation.

Some States have a practice of making international law part of their national laws, usually by incorporating it into the legal system once they ratify the treaty or agreement. However, the national law created in this way may not be as comprehensive as the original national laws.

There is a growing debate about whether there is a separate body of law, called a-national or lex mercatoria, that could transcend national boundaries and govern commercial transactions. Those who support this view point to the fact that many unwritten commercial customary laws are based on trade usages and do not involve any specific national jurisdictions. However, critics of the concept argue that detaching law from a national context is not possible.