The Warren Court ruled that teacher-led prayer in public schools violated the Establishment Clause of the First Amendment, which is designed to ensure a degree of separation between church and state. The Court first reached this conclusion in its 1962 decision Engel v. Vitale. The court dealt with a New York Board of Regents prayer that read: “Almighty God, we acknowledge our dependence upon Thee, and we beg Thy blessings upon us, our parents, our teachers, and our Country.”

“The New York laws officially prescribing the Regents’ prayer are inconsistent both with the purposes of the Establishment Clause and with the Establishment Clause itself,” Justice Hugo Black wrote for the Court majority. “It is neither sacrilegious nor anti-religious to say that each separate government in this country should stay out of the business of writing or sanctioning official prayers and leave that purely religious function to the people themselves and to those the people choose to look to for religious guidance.”

The Court reached a similar ruling in the companion cases School District of Abington Township v. Schempp and Murray v. Curlett (1963). These cases came from the states of Pennsylvania and Maryland respectively. The Pennsylvania law required the reading of ten Bible verses a day. The Maryland law required the reading of a section from the Bible or the Lord’s Prayer. The school district defendants argued that the prayer exercises advanced the secular purposes of promoting morality, contradicting a “materialistic trend” in society and teaching literature. The Court invalidated both state laws, describing them as “religious exercises … in violation of the command of the First Amendment that the Government maintain strict neutrality, neither aiding nor opposing religion.”