A phrase most famously used by Supreme Court Justice Black in the case of Everson v. Board of Education
. In discussing the Establishment Clause
of the First Amendment, Justice Black said that the clause erected a "wall of separation between church and state." He explained that this means, among other things, that the government cannot participate in the affairs of a religious group, set up a church, aid or prefer one religion over another, or aid or prefer religion over nonreligion.