LexisNexis Academic will help you identify and locate the texts of relevant laws and court decisions.
An interdisciplinary journal archive. It includes archives of over one thousand leading academic journals across the humanities, social sciences, and sciences, as well as select monographs and other materials valuable for academic work. Includes the Artstor image collections.
In some cases, you may wish to interpret as primary sources texts that originally were created as scholarly secondary sources. For example, if you are investigating the eugenics movement in the United States in the early twentieth century, you could look at articles on the topic that were published in academic journals in the 1910s and 1920s.
The following titles in Primo Search offer collections of primary sources that may be relevant to your project.
The Columbia Documentary History of Religion in America since 1945 by 
Rhetoric, Religion and the Civil Rights Movement, 1954-1965 by 
American Religion by Religious Liberty in the Supreme Court by This is only a sampling of the collections out there, just to get you started!