Which U.S. Supreme Court case established the 'Lemon test' for establishment clause?

Which U.S. Supreme Court case established the “Lemon test” for the Establishment Clause? Lemon v. Kurtzman established it in 1971.

The case combined challenges to Pennsylvania and Rhode Island programs that provided financial assistance to nonpublic, largely religious schools. The Court held that the arrangements violated the First Amendment’s Establishment Clause because they created excessive government entanglement with religion.

The resulting Lemon test asked whether a government action had a secular purpose, whether its principal or primary effect advanced or inhibited religion, and whether it fostered excessive government entanglement with religion. A challenged policy generally had to satisfy all three requirements.

The test governed many religious-liberty disputes for decades, but the Court later narrowed and criticized it. In Kennedy v. Bremerton School District in 2022, the Court said Establishment Clause analysis should instead be guided by historical practices and understandings, effectively abandoning Lemon. Everson, Abington, and Engel were important earlier Establishment Clause cases, but none created the three-part test.