Beginning with United States v. Carolene Products Co. (1938), the Court significantly revised its approach to the review of legislation. The Court presumes that legislation is constitutional and places the burden on the person challenging the law to prove that the law is not rationally related to a permissible government interest. Under this rational basis test, the Court strikes down very few pieces of legislation.
The Court’s review of legislation changes when the law affects a fundamental constitutional right. A fundamental right may arise explicitly from the Constitution or may be implied from the Constitution by the courts. The application of the due process clauses in the context of the protection of fundamental rights overlaps with the application of the Equal Protection Clause. If a law classifies certain people based on their exercise of a fundamental right, then the Court applies the Equal Protection Clause to the analysis. However, if the law restricts the fundamental rights of all persons, the Court engages in a due process analysis.
Under either the Equal Protection Clause or the due process clauses, where a law infringes upon a fundamental right, the Court subjects the law to close scrutiny. Unlike laws that are reviewed under the rational basis test, the Court presumes that a law that restricts a fundamental right is unconstitutional, and the state may only prove that the law is constitutional by showing that the law is “narrowly tailored” to further a compelling governmental interest. This standard is very difficult for the government to overcome.
One of the more controversial aspects of both due process and equal protection jurisprudence is the recognition of the fundamental rights that the Court has determined are implied in the Constitution. Few tend to question that citizens of the United States have a fundamental right to freedom of religion, since the Constitution explicitly provides this right. However, it is less clear that citizens have a general right to privacy since the Constitution says nothing about these types of rights. Nevertheless, the Court has recognized a number of these implied rights, which are often identified more generally as privacy rights.