The McCutcheon decision went after “aggregate” limits. Joined by the Republican National Committee, Shaun McCutcheon sued to challenge the maximum $74,600 allowed to be spent by donors on party committees and the maximum $48,600 that could be spent on contributions to candidates. On April 2, 2014, the Supreme Court struck down those limits. The decision led to single donors spending enormous amounts on joint fundraising committees.
Source: Campaign Legal Center
Source: Oyez
Sources: SCOTUSblog, Campaign Legal Center