The United States Supreme Court has held that State statutes which mandate that an employer not force an employee to work on his chosen Sabbath are violative of the Establishment Clause of the first amendment.
Estate of Thornton v. Caldor, Inc., 105 S. Ct. 2914 (1985).
Michael J. Hudock III,
Constitutional Law - First Amendment - Establishment Clause,
Duq. L. Rev.
Available at: https://dsc.duq.edu/dlr/vol24/iss3/9