evidence: When Senate Republicans silenced Sen. Elizabeth Warren, D-Mass., during debate over the nomination of Jeff Sessions to serve as attorney general, they sparked a furious response — but also used a rule that's meant to encourage civil debate. [...] First, the facts. Warren spoke on the Senate floor. She criticized Jeff Sessions, a Republican senator from Alabama and the nominee to lead the Justice Department. Warren read a letter from Coretta Scott King, written in 1986 as Sessions sought a post as a federal judge. Martin Luther King Jr.'s widow had questioned Sessions' work as a federal prosecutor: "Mr. Sessions has used the awesome powers of his office in a shabby attempt to intimidate and frighten elderly black voters." [...] According to Senate Republicans, Warren impugned the "conduct or motive" of Sessions, who is expected to be confirmed as attorney general Wednesday night.