During the 1980s, a colorful Washington figure used to stand in Lafayette Square near the White House holding a sign: “Arrest Me. I Question the Validity of the Public Debt. Repeal Section 4, Fourteenth Amendment to the U.S. Constitution.” That section reads: “The validity of the public debt of the United States, authorized by law, including debts incurred for payment of pensions and bounties for services in suppressing insurrection or rebellion, shall not be questioned.” As far as I know, the whimsical “protester” was never arrested; he wasn’t breaking any law. Congressional Republicans, if they force the United States into default on its debt, will be.

Even most journalists and policy wonks hadn’t heard of Section 4 until recently. But with a default on “the public debt” increasingly possible, many now find the subject gripping. What if the House Republican majority decides that they are just too angry to authorize repayment of the debt? They’d be violating the Constitution — but what would happen to the country, and to them?

During the debt-ceiling crisis of 2011, a number of scholars, including me, suggested that President Obama could end the standoff by proclaiming that Section 4 required him, as part of his duty to “take care that the laws be faithfully executed,” to set aside the debt ceiling and borrow enough money to fund payments on the debt. Obama later said his lawyers told him that was “not a winning argument.” This time around, White House Press Secretary Jay Carney has already said that “this administration does not believe that the 14th Amendment gives the power to the president to ignore the debt ceiling.”

Nevertheless, it’s useful to understand the history that brought Section 4 into being. Its story has parallels to the political situation in the United States today, almost a century and a half after the 14th Amendment was adopted.

In April 1865, Abraham Lincoln was killed by a southern assassin. Eight months later, the 13th Amendment was ratified and emancipation became the law of the land. But even amid the ashes of defeat and the triumph of Abolition, the South proclaimed itself not beaten, but triumphant. One influential southern newspaper explained in January 1866 that if the southern states’ population were counted proportionately in Washington, “the political power of the country will pass into the hands of the South, aided, as it will be, by Northern alliances.”

It was all too believable. Freedom for the slaves made their former masters stronger, not weaker, because southern states planned to accept full congressional representation for the freed blacks (as slaves, they had counted only as 3/5 of free people) — while permitting only whites to vote. Freed slaves now would count one for one, giving the South as many as 28 new House seats — and 28 more electoral votes — all to be determined by an all-white electorate.

After the war, the South wanted their state governments to repay the money they had borrowed to fund the Confederate war effort — and they wanted federal help to do it. If the Union would help not help pay back those debts, then they saw no reason why the U.S. national debt should be repaid either. After all, virtually all of it had been borrowed to fund the Union war effort. “If we’ve got to repudiate [the confederate debt], we may as well help the Democrats repudiate the debt on the other side too,” a delegate to Georgia’s new constitutional convention told a reporter, referring to the national debt. “What’s fair for one is fair for the other.” A South Carolina white put it more colorfully: “What, ruin us, and then make us help pay the cost of our own whipping? I reckon not!”

Northern politicians took the threat of resurgent southern power so seriously that they drafted the 14th Amendment, the longest in the Constitution. The former seceded states were excluded from Congress, and only allowed back in when their states ratified the amendment. In its five sections, it sought to systematically dismantle what northerners called “the slave power.” The Bill of Rights would apply in the South. Southern states would not get representation for black residents if the ballot remained all white. Former Confederate leaders could not serve in Congress. There would be no repayment for slaves. There would be no repayment of the Confederate debt. And the U.S. debt, amassed to pay for the war, was never to be repudiated — it was not even to be “questioned.”

Long after Reconstruction ended, the Supreme Court held that Section 4 remains an absolute command. “While this provision was undoubtedly inspired by the desire to put beyond question the obligations of the government issued during the Civil War, its language indicates a broader connotation,” Chief Justice Charles Evans Hughes wrote for the Court in a 1935 case called Perry v. United States. “Nor can we perceive any reason for not considering the expression ‘the validity of the public debt’ as embracing whatever concerns the integrity of the public obligations.”

A large number of today’s House Republicans seem to be channeling the ghosts of those long-ago secessionists. Beaten in an election, they still expect to rule, and they seem to recognize only the laws of which they approve. But last January, every member of the House swore to “support and defend” the Constitution, and “bear true faith and allegiance to the same.” They took that obligation “freely, without any mental reservation or purpose of evasion.”

There is no “14th Amendment exception” to that oath.

A century and a half ago, nearly a million Americans died to establish the United States as one nation. And when the battle ended, the new nation publicly pledged that it had undergone Lincoln’s “new birth of freedom” — that it would give due process and equality to all within its borders.

And that it would always pay its debts. On time. In full. Whether any willful group of renegades liked it or not.

PHOTO: U.S. Treasury Secretary Timothy Geithner holds up a copy of the U.S. Constitution before reading a passage from the 14th Amendment during a breakfast interview at the Newseum in Washington, May 25, 2011. REUTERS/Jonathan Ernst