Early this month, a group of Democratic members of Congress introduced an Abolition Amendment to the U.S. Constitution. Why, in the year 2020, does the Constitution need an amendment dealing with the abolition of slavery? Wasn’t that accomplished over a century and a half ago?

The problem is that the Thirteenth Amendment, ratified in 1865, which prohibits slavery throughout the country, allows for “involuntary servitude” as a “punishment for crime.” This loophole made possible the establishment of a giant, extremely profitable, system of convict labor, mainly affecting African-Americans, in the Jim Crow South. That system no longer exists but its legacy remains in the widespread forced labor of prisoners, who are paid far below the minimum wage. The Abolition Amendment would eliminate the Thirteenth Amendment’s “criminal exemption” by adding these words to the Constitution: “Neither slavery nor involuntary servitude may be imposed as a punishment for a crime.”

When enacted, the Thirteenth Amendment was recognized as a turning point in the history of the United States, indeed the entire world. When the House of Representatives approved it as the Civil War drew to a close, wild scenes of celebration followed. Members threw their hats in the air and embraced one another. Passage, wrote one newspaper, was “the crowning event of the war, indeed of the century.”

The Amendment’s wording, including the criminal exemption, was based on Thomas Jefferson’s proposed but never enacted Land Ordinance of 1784, which would have barred slavery in all the new nation’s territories. From there, it migrated to the Northwest Ordinance of 1787, which prohibited slavery in territories north of the Ohio River. Scholars have not explained why Jefferson devised this language. Perhaps he thought that labor was good for the character and would aid in the rehabilitation of prisoners. But the coupling of a ban on slavery with an exemption for convicted criminals quickly became embedded in American law. By the time of the Civil War, it could be found in the constitutions of a large majority of the free states. Such language survives in nearly half the state constitutions.

During the 1850s, Republicans, including Abraham Lincoln, popularized the claim that the Northwest Ordinance demonstrated that their new party was following the intentions of the founding fathers when it sought to bar slavery from the western territories. When it came time during the Civil War to write an amendment abolishing slavery, Charles Sumner, the abolitionist Senator from Massachusetts, proposed wording based on the 1791 French Declaration of the Rights of Man and the Citizen. His colleague Jacob Howard of Michigan rejected the idea of using a French model. “Good old Anglo-Saxon language” was adequate, he declared, and Congress gravitated to the wording of Jefferson’s ordinance.