To pass muster under the Establishment clause, governmental actions are scrutinized by courts, using a few key tests. One of the most often used and quoted is that outlined in the U.S. Supreme Court case of Lemon v. Kurtzman, (1971). In that case, the Court struck down a Pennsylvania state program providing aid to religious elementary and secondary schools, in the form of reimbursement for salaries, textbooks, and instructional materials. However, payment was premised upon the condition, among others, that the courses taught be secular in nature, similar to those presented in the public schools. Notwithstanding, the high court was presented with the issue of whether payment of salary supplements was unconstitutional under the Establishment clause.
The Lemon Court, under Chief Justice Warren Burger, outlined a three-prong test to be used in such challenges. To pass constitutional muster, a government action: (1) must have a secular legislative purpose; (2) its principal or primary effect must neither advance nor inhibit religion; and (3) it must not foster an excessive governmental entanglement with religion. The Court found the Pennsylvania school aid passed the first two prongs, but also found there was excessive entanglement with religion in its cumulative effect. While religion and government must co-exist in society and normally will interact at some points, they should not so overlap and intertwine as to cause persons to have difficulty differentiating between the two.
In 1997, the Supreme Court modified the,Lemon, test in its Agostini v. Felton, decision. It combined the last two prongs (effect and entanglement), now using only the “purpose” and “effects” prongs. It still used the “excessive entanglement” criterion, but within the context of determining whether a governmental action had a primary effect of advancing religion.
In other Establishment clause cases, courts also look to a test first advanced by Justice Anthony Kennedy, known as the “coercion” test. Under this test, government actions would be deemed constitutional unless they (1) provided direct aid to religion in a way that tended to establish a state church; or (2) coerced people to support or participate in religion against their will.
Still another, the “endorsement test” advanced by Justice Sandra Day O’Connor, asks whether the government action amounts to an endorsement of religion. Her primary focus was whether a government action conveyed “a message to non-adherents [of religion] that they are outsiders, not full members of the political community, and an accompanying message to adherents that they are insiders, favored members of the political community,” (from her dissenting opinion in the 1984 case of Lynch v. Donnelly). The endorsement test has been somewhat subsumed into the remaining Lemon prongs. The endorsement test is often used to consider cases in which the government is engaged in expressive activities such as graduation prayers, religious signs on government property, etc.