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).[4] 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.[9]
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.[4] 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.[4] 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.[4] 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.[4] In 2014, Freedom Partners was identified as the "poster child" for the rise of dark money.[4] 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.[4]
Approaching the 2018 midterm elections, in mid-September, just 15 groups accounted for three-quarters of the anonymous cash.[10]