Constitutional law: Individual rights - Freedom of religion

In the United States, freedom of religion is a constitutionally protected right provided in the religion clauses of the First Amendment. Freedom of religion is closely associated with separation of church and state, a concept advocated by Colonial founders such as Dr. John Clarke, Roger Williams, William Penn, and later Founding Fathers such as James Madison and Thomas Jefferson.

The freedom of religion has changed over time in the United States and continues to be controversial. Concern over this freedom was a major topic of George Washington's Farewell Address. Illegal religion was a major cause of the 1890–1891 Ghost Dance War. Starting in 1918, nearly all of the pacifist Hutterites emigrated to Canada when Joseph and Michael Hofer died following torture for conscientious objection to the draft. Some have since returned, but most Hutterites remain in Canada.

The long-term trend has been towards increasing secularization of the government. The remaining state churches were disestablished in 1820 and teacher-led public school prayer was abolished in 1962, but the military chaplaincy remains to the present day. Although most Supreme Court rulings have been accommodationist towards religion, in recent years there have been attempts to replace the freedom of religion with the more limited freedom of worship. Although the freedom of religion includes some form of recognition to the individual conscience of each citizen with the possibility of conscientious objection to law or policy, the freedom of worship does not.

Controversies surrounding the freedom of religion in the US have included building places of worship, compulsory speech, prohibited counseling, compulsory consumerism, workplace, marriage and the family, the choosing of religious leaders, circumcision of male infants, dress, education, oaths, praying for sick people, medical care, worshiping during quarantines, use of government lands sacred to Native Americans, the protection of graves, the bodily use of sacred substances, mass incarceration of clergy, both animal slaughter for meat and the use of living animals, and accommodations for employees, prisoners, and military personnel.