Merriman, Scott A., 1968-. Religion and the Law in America: An Encyclopedia of Personal Belief and Public Policy (Santa Barbara, CA: ABC-CLIO, 2007) - a comprehensive survey through more than 250 A-Z entries of one of the oldest and hottest debates in American history along with a series of broad, thematic essays, it examines the groups, laws, and court cases that have framed this ongoing debate
Encyclopedia of the First Amendment (Washington, DC: CQ Press, 2009)
Finkelman, Paul, ed. Religion and American Law: An encyclopedia (New York: Garland Pub., 2000)
Encyclopedia of the American Constitution (New York : Macmillan Reference USA, 2000) – 6 vols. At Law Library Reserve (circulation desk); its contents are listed in the catalog record, so you can search there before traveling over to the Law School
American Law Yearbook (WUSTL Libraries owns 1998-2005, 2011) - annual supplement to West's Encyclopedia of American Law that updates and expands the content with new topics, updates, biographies of prominent figures and government appointees, and other features. Each year's edition contains the full U.S. Supreme Court docket in addition to the non-Supreme Court cases. The 2011 edition includes a section on “Religion,” and I suspect the others do as well.
The Oxford Guide to United States Supreme Court Decisions, 2nd ed. (Oxford; New York: Oxford University Press, 2009) - eBook
The Oxford Companion to the Supreme Court of the United States – WUSTL Libraries own the 1st (1992) and 2nd ed. (2005) in print and as an eBook
Lieberman, Jethro K. A Practical Companion to the Constitution: How the Supreme Court has ruled on issues from abortion to zoning (Berkeley: University of California Press, 1999)
Making of Modern Law: U.S. Supreme Court Records and Briefs, 1832-1978 - This database is the world's most comprehensive online collection of records and briefs brought before the Supreme Court. It facilitates access to transcripts, applications for review, motions, petitions, supplements, and other official papers for approximately 150,000 Supreme Court cases, the majority consisting of those for which the Court did not give a full opinion. The inclusion of lawyers' briefs will help you build your case, as they often incorporate considerable historical, economic, and sociological data. In addition to full text, keyword searching, the collection can be searched by case name, variant case name, document type, document file date, Supreme Court term year, docket number, alternate docket number, U.S. Reports citation, Supreme Court Reporter citation, Lawyer's Edition citation, and opinion date. There are other collections in the Making of Modern Law series, including Legal Treatises, 1800-1926, Trials, 1600-1926, and Primary Sources, 1620-1926.
Nexis Uni (formerly LexisNexis academic) - in addition to news, Nexis Uni also includes extensive legal sources for federal and state cases and statutes and U.S. Supreme Court decisions since 1790
Hein Online – contains more than 900 searchable full-text law journals and many legal resources
A selection of titles that one should not consider exhaustive:
How Free Can Religion Be? (Champaign: University of Illinois Press, 2006) - discusses eight provocative Supreme Court decisions to track the evolution of Free Exercise and Establishment Clause doctrine
Flowers, Ronald B. (Ronald Bruce), 1935-. That Godless Court?: Supreme Court decisions on church-state relationships (Louisville, KY: Westminster/John Knox Press, 1994)
Between Church and State: Religion and public education in a multicultural America, 2nd ed. (Baltimore: Johns Hopkins University Press, 2016)
the landmark law cases & American society series (Lawrence: University Press of Kansas):
Dierenfield, Bruce J., 1951-. The Battle over School Prayer: How Engel v. Vitale changed America (2007)
O'Brien, David M. Animal sacrifice and religious freedom: Church of the Lukumi Babalu Aye v. City of Hialeah (2004)
Peters, Shawn Francis, 1966- . The Yoder Case: Religious freedom, education, and parental rights (2003)
Long, Carolyn Nestor. Religious Freedom and Indian Rights: The Case of Oregon v. Smith (2000)
Religion and law -- United States
Church and state -- United States
Freedom of religion -- United States
Religion in the public schools -- United States
United States. Constitution. 1st Amendment
Prayer in the public schools -- Law and legislation -- United States
Religious minorities -- Legal status, laws, etc. -- United States