Lemon v. Kurtzman (1971) was a landmark, 8–1, Supreme Court decision marking a victory for the liberal interpretation of separation of church and state. The decision established a test called the "Lemon Test" which was used to determine whether or not federal funds could be appropriated to be spent at a Catholic or other parochial school.
Under the "Lemon Test," to pass constitutional muster as a law that does not violate the Establishment Clause, a law must:
- Have a legitimate secular purpose, and,
- Not have the primary effect of either inhibiting or advancing religion, and,
- Not promote excessive entanglement between church & state.
Any law can be invalidated on any one of the above three requirements of the Lemon Test.
In practice the ruling has been applied sporadically to impose a test for separation of church and state under the First Amendment that is hostile to almost any religious expression on government property.
The "Lemon Test" was the one applied to invalidate the Dover School Board's intelligent design policy in Kitzmiller vs. Dover Area School District.
It was overruled in 2022 by Kennedy v. Bremerton School District.