The purpose of this study was to determine the philosophical orientation of each sitting Justice on matters pertaining to the Establishment Clause of the First Amendment to the United States Constitution. A second purpose is to determine whether their philosophies change based on the issues involved.

The research questions that drove this analysis are:

1. What theories of original intent can be derived from the literature?
2. To which variation of original intent, separationism or nonpreferentialism, do the individual Justices subscribe?
3. What are the various Establishment Clause issues that have been heard by the Court?
4. Do the individual Justices’ philosophies change depending on the issue?

By studying the text of the First Amendment, events surrounding its passage and other writings of the Framers of the Constitution, scholars have posited two theories of the original intent of the Framers to explain the meaning of “an establishment of religion.” The first theory is termed nonpreferentialism. Nonpreferentialists argue that government may support religion so long as that support is nondiscriminatory among religious sects. The second theory, separationism, states that government may not support one, any or all religions. Separationists argue that a "wall of separation” should exist between church and state while nonpreferentialists opine that no such wall was intended by the Framers.

The United States Supreme Court has jurisdiction over issues involving the establishment of religion. The individual Justices have certain predilections with regard to governmental support of religion and have written opinions in cases and scholarly articles in which they articulate their philosophies.

Using traditional legal research methods, this study has demonstrated that of the seven sitting Justices that have written opinions or scholarly articles pertaining the Establishment Clause, Rehnquist, Scalia and Thomas, are consistently nonpreferentialist in their philosophical orientation. One justice, Stevens, is consistently separationist. Souter has written consistently separationist opinions, yet joined O’Connor’s nonpreferentialist concurrence in one case. Kennedy, and O’Connor are neither consistently separationist nor nonpreferentialist. The philosophical orientation of those Justices changes based on the nature of the Establishment Clause issue.