Kurt T. Lash, Loyola Law School Los Angeles, has posted on SSRN his article "The Second Adoption of the Free Exercise Clause: Religious Exemptions Under the Fourteenth Amendment." It appeared in the Northwestern University Law Review (1994).
More folks seem to be using SSRN to make earlier articles more accessible, which strikes me as a great idea. It your journal or press wouldn't let you post on-line when an essay was published, you might want to check back later.
Here's Lash's abstract: This Article explores the proposition that the Free Exercise Clause was adopted a second time through its incorporation into the Privileges or Immunities Clause of the Fourteenth Amendment and that the scope of the new Free Exercise Clause was intended to include protections un-anticipated at the Founding. Contrary to Jeffersonian notions of "separate spheres," the nation by the time of Reconstruction had experienced decades of clashes resulting from the overlapping concerns of religion and government. In particular, the suppression of slave religion called into question the government's power to interfere, even indirectly, with legitimate religious exercise. Accordingly, the Privileges or Immunities Clause incorporated a conception of religious liberty vastly different from that intended in 1791 and constitutes a constitutional modification of the original "rights of conscience." Religious exemptions from generally applicable laws, considered unnecessary and improbable at the Founding, now became necessary and proper.