Religious freedom has long been an important value in American society. Its significance can be seen in the fact that the First Amendment of the Bill of Rights begins: “Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof.” These clauses at first applied only to Congress and federal laws, but in the 1940s the Supreme Court ruled that they also applied to state and local laws.

The practical application of the First Amendment’s clauses on religious freedom has been the source of much debate. In recent years, Congress and the Supreme Court have considered whether people should be exempt from laws that are in conflict with their religious beliefs—even if the laws are not specifically directed against religion.

The 1990 case of Employment Division v...