WASHINGTON (AP) — A fistfight on the Senate floor involving two Southern “gentlemen” gave rise to Rule 19, the arcane Senate directive that Republicans used more than a century later to silence Democratic Sen. Elizabeth Warren. GOP lawmakers rebuked Warren Tuesday night for speaking against colleague and Attorney General-nominee Jeff Sessions.

She was silenced for reading the letter that Coretta Scott King wrote three decades ago criticizing the Alabama senator’s record on race. Senators barred Warren from speaking on the Senate floor until Sessions’ confirmation vote.

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CONDUCT UNBECOMING

Rule 19 states that senators may not “directly or indirectly, by any form of words impute to another senator or to other senators any conduct or motive unworthy or unbecoming a senator.”

It states that when, in the opinion of the presiding officer, a senator violates that decorum, the presiding officer “shall call him to order and … he shall take his seat.”

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RAUCOUS HISTORY

In the Senate, where men are referred to as “gentleman” and women are called “gentle lady,” the rule stems from a notorious 1902 incident in which two South Carolina lawmakers got into a fistfight on the Senate floor. According to the Senate historian’s office, Sen. John McLaurin raced into the Senate chamber and said fellow Democrat Ben Tillman was guilty of “a willful, malicious, and deliberate lie.”

Tillman — a fiery populist who had earned the nickname “Pitchfork Ben” for threatening to bring a pitchfork to prod then-President Grover Cleveland to act on the economy — spun around and punched McLaurin squarely in the jaw. The Senate “exploded in pandemonium as members struggled to separate both members.” The fracas ended, “but not without stinging bruises both to bystanders and to the Senate’s sense of decorum,” according to an account on the historian’s office website.

The Senate censured both men and added to its rules the provision that survives today as part of Rule 19.

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SELECTIVE ENFORCEMENT

Enforcement of Rule 19 has been rare, and the historian’s office wasn’t sure when it was last enforced.

Some longtime Capitol observers recalled a 1988 dispute between Sen. John Heinz, R-Pa., and Sen. Phil Gramm, R-Texas. Heinz said Gramm broached Senate protocol with caustic remarks. Gramm withdrew the language in question. There was no official rebuke.

Heinz was also involved in a 1979 dispute with fellow Republican Sen. Lowell Weicker of Connecticut. After heated words, the two men shook hands and no further action was taken.

Democrats cited more recent statements that appeared to violate Rule 19, but in which no action was taken:

—In 2015, Sen. Ted Cruz, R-Texas, said McConnell “looked me in the eye” and “told every Republican senator … a simple lie.”

— In 2016, Sen. Tom Cotton, R-Ark., lambasted the “cancerous leadership” of then-Senate Minority Leader Harry Reid, D-Nev.

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FIGHT CONTINUES:

Sen. David Perdue, R-Ga., said Senate Minority Leader Chuck Schumer, D-N.Y. had engaged in a “tear-jerking performance” that “belongs at the Screen Actors Guild awards” as he opposed President Donald Trump’s travel ban on some Muslim countries. No rebuke followed.

Other Democratic senators read from King’s letter in the Senate chamber Wednesday after Warren was told to sit down. None was punished.

Follow Matthew Daly: http://twitter.com/MatthewDalyWDC

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This story has been corrected to … With BC-US–Senate Rancor.