Liberal advocacy groups that publish widely cited lists of purported "hate groups," tarring a diverse spectrum of conservative organizations, are facing defamation claims alleging they knowingly spread falsehoods about those organizations' beliefs and activities. A federal judge recently refused to dismiss litigation against the 52-year-old Southern Poverty Law Center for designating the Georgia-based Dustin Inman Society, which promotes "legal, sustainable and reduced immigration," as an "anti-immigrant hate group." The designation came seven years after SPLC told The Associated Press the label would be too strong for what it called a "nativist" group that works "through the political process." That has...