In theory, the Establishment Clause of the First Amendment to the United States Constitution, together with that Amendment's Free Exercise Clause, form the constitutional right of freedom of religion. The Establishment Clause and the Free Exercise Clause together read:
The Establishment Clause acts as a double security, prohibiting both control of the government by religion and political control of religion by the government. By it, the federal government of the United States and, by later extension, the governments of all U.S. states and U.S. territories, are prohibited from establishing or sponsoring religion.