A national law is a law that exists inside of a particular nation (State). National laws can either come from the government itself (through enactment), or from the courts through decisions made by judges, called case law. A national law can also include an international treaty or law, if that is what the State chooses to do.
Neither slavery nor involuntary servitude shall exist within the United States or any place subject to their jurisdiction, nor shall there be any manufacture of any kind of machinery for its purposes. This article of the Constitution voids any law or act of the Government which violates it.
There are a variety of resources available to learn more about federal laws and the lawmaking process in Congress, including finding legislation by name or keyword, researching bills, learning about the impeachment process, and obtaining copies of government files. In addition, there are a number of websites where you can access copyrighted government creative works.
Unlike international law, which is created and enforced by the United Nations and a few other organizations, national law deals with laws and rules that are enforced by the government of one country, like the United States. Professionals who want to work in the field of law should be aware of the distinction between international and national laws, as the former is generally more difficult for individuals to apply in their day to day lives than the latter. International law is usually more specific about conventions and treaties, whereas national law is more focused on acts and constitutions of individual counties or states, and sometimes even cities.