The Establishment Clause is a provision in the First Amendment of the U.S. Constitution, extended to apply to the states through the Fouteenth Amendment, which prohibits laws dealing with the establishment of religion. Neither the state or federal government may enact laws which aid one or all religions, or give a preference to one religion over another. The Establishment Clause was intended to prohibit the federal government from declaring and financially supporting a national religion.
Some governmental activity related to religion has been declared constitutional by the Supreme Court. For example, providing bus transportation for parochial school students and the enforcement of "blue laws" is not prohibited. There is often tension between application of the Establishment Clause and the Free Exercise Clause, which protects the exercise of religious freedom. Common issues involving the Establishment Clause involve the inclusion of religious symbols in public holiday displays and school prayer, among others.
The Engel v. Vitale decision of the U.S. Supreme Court in 1962 prohibited state-mandated prayer in public schools classrooms. However, students may express religious preferences in various ways, such as carrying Bibles or other religious texts with them on the school bus, and praying alone or in groups on school grounds, or in classrooms outside of regular teaching hours. Students may also form a Bible study club or any other religious club, if another student-led group is already allowed in the school, and may hand out religious materials.