<P> The rise of dark money groups was aided by the U.S. Supreme Court decisions in FEC v. Wisconsin Right to Life, Inc. (2008) and Citizens United v. FEC (2010). In Citizens United, the Court ruled (by a 5--4 vote) that corporations and unions could spend unlimited amounts of money to advocate for or against political candidates . </P> <P> In some elections, dark money groups have surpassed traditional political action committees (PAC) and "super PACs" (independent - expenditure - only committees) in the volume of spending . In 2012, Freedom Partners had the ninth - highest revenues among all U.S. trade associations which filed tax returns that year, more than "established heavyweights" such as the American Petroleum Institute, PhRMA, and U.S. Chamber of Commerce . Freedom Partners largely acted as a conduit for campaign spending; of the $238 million it spent in 2012, 99 percent went to other groups, and Freedom Partners itself did not have any employees . This was a major distinction between other high - revenue trade associations, which typically have many employees and devote only about 6 percent of spending to grants to outside groups . In 2014, Freedom Partners was identified as the "poster child" for the rise of dark money . The largest and most complex network of dark money groups are funded by conservative billionaire business magnates Charles and David Koch; the Koch brothers' network accounted for about a quarter of dark money spending in 2012 . </P> <P> Approaching the 2018 midterm elections, in mid-September, just 15 groups accounted for three - quarters of the anonymous cash . </P> <P> According to the Center for Responsive Politics, dark money (which it defined as funds from outside groups that did not publicly disclose donors, plus groups that received a substantial portion of their contributions from such nondisclosing groups) accounted for nearly 44% of outside spending in the 2010 election cycle . </P>

Dark money is political money that comes from donors who do not have to be disclosed