The First Amendment to the United States Constitution guarantees freedom of religion, speech, assembly, and the press.

The Establishment Clause of the First Amendment prohibits the government from establishing a religion, interfering with religious practices, or favoring one religion over another.

The Free Exercise Clause of the First Amendment protects the right to practice one's religion freely, express one's religious beliefs, and assemble with others for religious purposes.

In West Virginia State Board of Education v. Barnette (1943), the Supreme Court held that the government cannot compel individuals to participate in religious activities, such as saluting the flag.

In Engel v. Vitale (1962), the Supreme Court held that the government cannot require public schools to lead students in prayer.

In Lemon v. Kurtzman (1971), the Supreme Court held that the government cannot provide financial aid to religious schools.

In Zelman v. Simmons-Harris (2002), the Supreme Court held that the government can provide financial aid to religious schools if the aid is neutral and does not favor one religion over another.

In Trinity Lutheran Church of Columbia, Inc. v. Comer (2017), the Supreme Court held that the government can provide financial aid to religious schools for secular purposes.

In Espinoza v. Montana Department of Revenue (2020), the Supreme Court held that the government cannot discriminate against religious schools in the provision of public benefits.

In Town of Greece v. Galloway (2014), the Supreme Court held that the government cannot prohibit religious displays on public property.

In Town of Greece v. Galloway (2014), the Supreme Court held that the government cannot prohibit religious prayers at public meetings.

In Salazar v. Buono (2010), the Supreme Court held that the government cannot prohibit religious symbols on public property.

In Hosanna-Tabor Evangelical Lutheran Church and School v. EEOC (2012), the Supreme Court held that the government cannot prohibit religious employers from discriminating against employees on the basis of their religious beliefs.

In Burwell v. Hobby Lobby Stores, Inc. (2014), the Supreme Court held that the government cannot prohibit religious businesses from refusing to provide services to same-sex couples.

In Carson v. Makin (2022), the Supreme Court held that the government cannot prohibit religious schools from discriminating against LGBTQ students.