Louisiana butchers challenged a New Orleans slaughterhouse monopoly under the newly ratified Fourteenth Amendment. The Court, 5–4, read the Privileges or Immunities Clause to protect only a narrow set of rights of national (not state) citizenship — access to seaports, protection on the high seas, and the like. The reading gutted what might have been the Fourteenth Amendment's most potent civil-rights engine, forcing later Courts to route civil-liberties claims through the Due Process and Equal Protection Clauses instead. The Slaughter-House Cases remain among the most consequential missed opportunities in American constitutional history.