In a previous book, the author sought to establish that the likely original meaning of the Fourteenth Amendment's Privileges or Immunities Clause was that it guaranteed equality in fundamental rights under state law. The central provisions of the first section of the Amendment -- due process of law, protection of the laws, and the privileges and immunities of citizenship -- had long-established antebellum legal meanings. Due process of law primarily meant there had to be established law before one could be deprived of life, liberty, or property, and any violation of that established law had to be adjudicated according to known and established procedures. The protection of the laws was the other side of the coin: It was the legal protection the government had to extend against private invasions of private rights, principally judicial remedies and physical protection from violence. The protection of the laws was the heart of the social compact: Men exit the state of nature and give up some of their executive power and agree to obey the sovereign -- they agree to give allegiance -- in exchange for the sovereign's protection against private violence and private invasions of rights.

The antebellum legal background is crucially important for understanding the original meaning of the Amendment's privileges or immunities provision because it is that provision that therefore must accommodate the central goal of the Amendment's drafters of constitutionalizing the Civil Rights Act of 1866. That act guaranteed equality in civil rights under state law. Although many Republicans believed the act was justified under the Thirteenth Amendment's enforcement clause, many, including John Bingham, the principal author of the Fourteenth Amendment's first section, believed the Act to be unconstitutional. Moreover, it was necessary to enshrine the civil rights principle in the Constitution itself, lest the Democrats take over and repeal that legislation; Congress needed, in the words of Representative and future President James Garfield, "to lift that great and good law above the reach of political strife, beyond the reach of the plots and machinations of any party, and fix it in the serene sky, in the eternal firmament of the Constitution."

Yet, if the due process and protection of the laws clauses in the Amendment had their historical legal meanings, they would not accomplish that central objective. Due process does not guarantee equal rights, only that whatever rights one has will not be taken away without established law and known procedures. Nor does equal protection of the law guarantee equal rights, but rather guarantees only that whatever rights one possesses will be equally protected against, say, Ku Klux Klan violence. That leaves only the privileges or immunities provision, whose language does the necessary work. The Reconstruction generation understood that civil rights defined and regulated under state law, including contract and property rights, were fundamental rights that all free governments had to secure. They were, in other words, the "privileges and immunities of citizens of the United States," shared by all citizens, though states may have regulated the rights differently. A state would "abridge" those rights by giving a lesser set of rights to a disfavored class.