 In the debates leading up to World War I , a number of isolationist senators filibustered bills that Wilson considered important . The filibusters lasted for weeks and twice lasted for over three months . Wilson and the bills ' supporters requested that Marshall put a gag @-@ order in place to cut off debate , but he refused on ethical grounds , allowing a number of bills to be defeated in hopes that opposition would eventually end their filibuster . Among the defeated bills was one allowing merchant ships to arm themselves , and another allowing the US government to make direct arms sales to the allies . Despite their victories , the small group of senators continued to lock up the senate to prevent any pro @-@ war legislation from passing . In response , Marshall led the Senate to adopt a new rule on March 8 , 1917 , allowing filibusters to be broken by two @-@ thirds of voting Senators . This replaced the previous rule that allowed any senator to prolong debate as long as he desired . The rule has been modified several times , most prominently that the current rule requires three @-@ fifths of all Senators , not only the ones voting . 
