Available here. An outstanding brief, as one might expect. The bulk of the brief (21 pages, comprising Part I) shows that from the Founding Era into through the framing of the Fourteenth Amendment, national citizenship was paramount to state citizenship. Part II briefly argues that Slaughterhouse violated canons of constitutional construction–such as by interpreting the Privileges or Immunities Clause to make it nothing more than a reiteration of the Supremacy Clause.
Finally, Part III (pp. 27-33) argues that enforcing the Privileges or Immunities Clause will not undermine the Court’s prior so-called “substantive due process” jurisprudence. The brief shows that long before the 14th Amendment, “due process” was understood to mean that certain inherently unfair government actions were beyond the scope of lawful government powers–even if the government had followed proper procedures, such as public hearings. In the Supreme Court, the doctrine is as old as Daniel Webster’s argument in the 1819 Dartmouth College case, was always solidly established in American understanding of “due process,” and was so understood by the Framers of the Fourteenth Amendment.
Lead author on the brief is Timothy Sandefur of the Pacific Legal Foundation, which is also a party on the brief. You can listen to a podcast with Sandefur discussing the brief. The PLF’s Liberty Blog has some very interesting posts on the historical background of the Slaughterhouse cases.
United States v. Cruikshank, which was decided a few years later, finished off the job of judicial nullification of the Privileges or Immunities clause. Since that Court allowed some white domestic terrorists get away with mass murder of armed blacks who had assembled in a Louisiana courthouse, Cruikshank might appropriately have been captioned Slaughterhouse II.