* 1982 decree intended to stop alleged ballot box abuse * Republicans cited free speech, voter fraud in bid to end decree (Adds paragraphs 3-9, case citation, byline) By Jonathan Stempel WASHINGTON, Jan 14 (Reuters) - The U.S. Supreme Court on Monday refused to hear a legal challenge by the Republican National Committee to dissolve a 1982 decree designed to stop the improper suppression of voting by particular groups.