Which of the following is NOT a source of law in the United States?

Civil rights law is not considered a separate source of law in the same way that constitutional law, statutory law, and administrative law are.

Constitutional law refers to the framework established by the Constitution, which is the supreme law of the land. It sets out the fundamental principles and structures of government and guarantees various rights to individuals. Statutory law encompasses laws enacted by legislatures at both the federal and state levels, which are codified and can be enforced. Administrative law involves rules and regulations created by governmental agencies, meant to carry out the intent of statutory law and provide specific guidelines pertaining to various regulatory areas.

Civil rights law, while vital in protecting individuals' rights, often derives from constitutional and statutory law rather than being a distinct source of law itself. It is primarily concerned with protecting the rights of individuals against discrimination and ensuring equal treatment, but it operates within the frameworks established by the other three sources of law. Hence, it is seen as a subset or application of the broader categories of law rather than an independent source.