From its earliest days, the Senate has consistently stressed the importance of decorum in its proceedings. Of the Senate's first 20 rules, 10 dealt with proper behavior. Vice President Thomas Jefferson included in his now-classic Manual of Parliamentary Practice a telling passage that reads as if it had been taken from a schoolroom wall. "No one is to disturb another in his speech by hissing, coughing, spitting, speaking or whispering to another; nor to stand up or interrupt him; nor to pass between the Speaker and the speaking member; nor to go across the [Senate chamber], or to walk up and down it, or to take books or papers from the [clerk's] table, or write there."

On February 22, 1902, John McLaurin, South Carolina's junior senator, raced into the Senate Chamber and pronounced that state's senior senator, Ben Tillman, guilty of "a willful, malicious, and deliberate lie." Standing nearby, Tillman spun around and punched McLaurin squarely in the jaw. The chamber exploded in pandemonium as members struggled to separate both members of the South Carolina delegation. In a long moment, it was over, but not without stinging bruises both to bystanders and to the Senate's sense of decorum.

Although Tillman and McLaurin had once been political allies, the relationship had recently cooled. Both were Democrats, but McLaurin had moved closer to the Republicans, who then controlled Congress, the White House, and a lot of South Carolina patronage. When McLaurin changed his position to support Republicans on a controversial treaty, Tillman's rage erupted. With McLaurin away from the chamber, he had charged that his colleague had succumbed to "improper influences."

On February 28, 1902, the Senate censured both men and added to its rules the provision that survives today as part of Rule XIX: "No senator in debate shall, 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."