For a law to be considered constitutional under the Establishment Clause, the law must have a legitimate secular purpose, must not have the primary effect of either advancing or inhibiting religion, and must not result in an excessive entanglement of government and religion (Overruled by Groff v. DeJoy, 600 U.S. 447 (2023)) Decided June 28, 1971 (argued March 3, 1971). Opinion of the Court: Warren E. Burger → go there Applied: the First Amendment → go there Topic: Freedom of religion. Lemon v. Kurtzman, 403 U.S. 602 (1971), was a case argued before the United States Supreme Court. The court ruled in an 8–0 decision that Pennsylvania's Nonpublic Elementary and Secondary Education Act from 1968 was unconstitutional and in an 8–1 decision that Rhode Island's 1969 Salary Supplement Act was unconstitutional, violating the Establishment Clause of the First Amendment. The act had allowed the Superintendent of Public Schools to reimburse private schools for the salaries of teachers who taught in these private elementary schools from public textbooks and with public instructional materials. Wiki link