This week, Republican governors across the country escalated their conflict with the Biden administration over the southern border by invoking the same legal theory that slave states wielded to justify secession before the Civil War. Texas Gov. Greg Abbott, joined by 25 other GOP governors, now argues that the Biden administration has violated the federal government’s “compact” with the states—an abdication that justifies state usurpation of federal authority at the border. This language embraces the Confederacy’s conception of the Constitution as a mere compact that states may exit when they feel it has been broken. It’s dangerous rhetoric that transcends partisan grandstanding. And as before, it’s being used to legitimize both nullification and dehumanization.

Consider the very first line of a statement Abbott issued on Wednesday that was subsequently backed by the other Republicans, which states, “The federal government has broken the compact between the United States and the states.” That language is strikingly similar to the very first line of the secession ordinances passed by slave states when they purported to leave the union. Most of these ordinances began with a declaration that the state sought “to dissolve the union” that was “united under the compact” known as the Constitution. It was this “compact”—not national sovereignty, but a contract among states and the federal government—that constituted the United States of America. The secession ordinances asserted that the federal government, and the president especially, owed certain constitutional duties to the states under this contract. It had allegedly abdicated those duties by threatening to restrict slavery and disrespecting the rights of Southern states in other ways inextricably linked to the maintenance of white supremacy. Any state, these ordinances concluded, was therefore entitled to depart the union and become “free and independent” once more.

President Abraham Lincoln was staunchly opposed this so-called compact theory. As he explained in his first inaugural address, “The........

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