Colombia is rich in rebels, but the government of President Virgilio Barco has slowly been coming to terms with them. The first to switch from outlaw group to political party is M-19, a 1970s leftist band of middle-class guerrillas who moved from symbolic displays of conscience, like holding "hostage" the sword of Latin American liberator Simon Bolivar, to acts of terror and violence. In 1985 M-19 bungled a takeover of Bogota's Palace of Justice, triggering a battle with government forces that left more than 100 dead.
Last week M-19 agreed to put down its guns. Saying he was "ready for the...