Former Supreme Court Justice David Souter gave a big commencement speech last week at Harvard University where he criticized originalism—the school of thought that says the Constitution should be read according to its original public meaning—for having "only a tenuous connection to reality." According to liberal pundit E.J. Dionne, Souter's speech proves that liberal champions of the "Living Constitution" now "have fighting words of their own."

Fighting words, maybe. But accurate words? Not exactly.

Souter argued that originalism has nothing useful to say about the racial segregation imposed by the South's Jim Crow regime, and claimed that it was only thanks to living constitutionalism that the Supreme Court eventually nullified the vile doctrine of "separate but equal." Here's the relevant portion of his commencement speech:

[Brown v. Board of Education] ended the era of separate-but-equal, whose paradigm was the decision in 1896 of the case called Plessy v. Ferguson, where the Supreme Court had held it was no violation of the equal protection guarantee to require black people to ride in a separate railroad car that was physically equal to the car for whites. One argument offered in Plessy was that the separate black car was a badge of inferiority, to which the court majority responded that if black people viewed it that way, the implication was merely a product of their own minds. Sixty years later, Brown held that a segregated school required for black children was inherently unequal. For those whose exclusive norm for constitutional judging is merely fair reading of language applied to facts objectively viewed, Brown must either be flat-out wrong or a very mystifying decision. Those who look to that model are not likely to think that a federal court back in 1896 should have declared legally mandated racial segregation unconstitutional. But if Plessy was not wrong, how is it that Brown came out so differently?

Here's the problem with Souter's claims: The Plessy decision is wrong under an originalist reading of the Constitution. Originalism includes the original public meaning of the 14th Amendment, which commands: "No State shall make or enforce any law which shall abridge the privileges or immunities of citizens of the United States." Among those privileges or immunities is the right to economic liberty. Remember that the origins of the 14th Amendment lie in the anti-slavery politics of the Radical Republicans who drafted it and spearheaded its ratification. Their philosophy centered on a radically libertarian form of self-ownership, one that included both the right to armed self-defense and the right to liberty of contract. That philosophy was enshrined in the Constitution when the 14th Amendment was ratified in 1868.

In Plessy, the Supreme Court upheld a Louisiana law that forbid railroad companies from selling first-class tickets to black customers. That law was a blatant violation of economic liberty under the 14th Amendment and should have been struck down as such. That the Supreme Court failed to do so isn't an indictment of originalism, it's an indictment of the justices who failed to take the Constitution at its word.