John Steele Gordon writes for City Journal about the origins of a controversial U.S. Senate procedure.

The word comes from the Spanish for “freebooter,” another name for pirate. In the mid-nineteenth century, it signified men, usually Americans, who tried to seize control of weak Central American countries. (The most famous of these was William Walker, the so-called “grey-eyed man of destiny,” who briefly became president of Nicaragua in 1856.) How the word came to be used as a name for dilatory legislative tactics is unknown; the first known example of this meaning dates to 1863.

The tactic was rarely deployed immediately after its creation. It was used once in 1837 to prevent a censure of President Andrew Jackson from being expunged, and once in 1841 to prevent the establishment of a new national bank. Ending legislative debate in the Senate required unanimous consent until 1917, when, after Germany declared unrestricted submarine warfare, 12 antiwar senators successfully filibustered a bill that would have armed merchant vessels. At the request of President Woodrow Wilson, the Senate voted 76–3 to establish a cloture rule that would allow two-thirds of senators present and voting to shut down debate. …

… Later changes led to the modern incarnation. Until 1970, a filibuster brought the Senate to a halt until either the motion was abandoned or cloture was invoked. That year, a rules change allowed the Senate to consider more than one motion at a time. In 1975, the number of votes needed to invoke cloture was reduced to three-fifths of the whole Senate: 60 votes. (Cloture for rules changes still requires two-thirds of those present and voting.) Naturally, when senators no longer needed to hold the floor to filibuster, the tactic became much more common. The effect was to require 60 votes to pass legislation or confirm nominations in the Senate, something not contemplated by the Founders—nor, of course, forbidden by them.

Deepening partisan divisions leave the filibuster’s future uncertain.