But was it? Not by a long shot; when it comes to misconduct, Congress has a long history. Congressmen have pulled guns on each other. They’ve shoved and punched each other, and smacked at foes with fireplace tongs. They’ve engaged in mass brawls, toppling desks, tossing spittoons and, in one case, yanking off a toupee. The most famous violence in congressional history is the caning of the abolitionist Senator Charles Sumner of Massachusetts by Representative Preston Brooks of South Carolina on the Senate floor in 1856, but it was not an anomaly.

Nor is Ms. Pelosi alone in violating traditions for all to see; it was far from the first time that members of Congress met alleged lies with bold displays of open contempt. In 1790, Representative Aedanus Burke of South Carolina showed his feelings with a flourish after Alexander Hamilton, the Treasury secretary, slurred the Southern militia during an Independence Day speech. Hamilton had said that Southern troops were dispirited and in disarray before the arrival of Gen. Nathanael Greene. Burke — outraged and hoping to impress folks back home — used the theater of Congress to have his say. Turning toward the visitor gallery, he declared, “In the face of this assembly and in the presence of this gallery … I give the lie to Colonel Hamilton.” Onlookers were stunned.

Representative Louie Gohmert of Texas did much the same when President Obama discussed his health care plan before the House in 2009, waving a handwritten sign that read, “What Plan?” “The things he was saying were certainly not true of the only bill we had at the time,” Mr. Gohmert later said. On that same night, Representative Joe Wilson of South Carolina shouted “You lie!” at the president for a similar reason.

By far, the most skilled practitioners of this showy statecraft were Southern slaveholders in the decades leading up to the Civil War. Threatened by even the hint of opposition to slavery, they used bold public threats during debate to frighten their foes into compliance or silence, tossing off insults or dangling duel challenges to set an example. Faced with the choice of a fistfight or a duel — or the humiliation of avoiding one — most men backed down or held back. For Southerners, transgressing rules was part of the point; it was a show of power.

Senator Rand Paul of Kentucky used the same form of showmanship when he exposed the alleged whistle-blower’s name during impeachment proceedings last Tuesday. Days after Chief Justice John Roberts refused to read a question from Mr. Paul that revealed the name, Mr. Paul did the deed himself. During a period reserved for impeachment speeches, he read his question aloud while standing next to a large blue poster with the name in bold yellow, endangering the whistle-blower and violating the spirit of whistle-blower protection laws in the process; although those laws are meant to protect informants from retaliation, they don’t explicitly stop members of Congress or the president from revealing names. Tradition and ethics alone keep them silent.