Modern campaign finance law stems from the Federal Election Campaign Act (FECA), first enacted in 1971 and amended in 1974, 1976, and 1979. FECA mandated reporting requirements similar to those in place today, such as quarterly disclosure of a political committee’s contributions and spending. FECA also limited spending on media advertisements, though that restriction was later declared unconstitutional. The law provided a framework for the creation of political action committees.

The 1974 amendments, passed in the wake of the Watergate scandal, placed limits on contributions and spending by campaigns. Congress also established the Federal Election Commission, charging it with enforcing the law. The legislation put in place a system for disclosure and created a public financing system for presidential candidates in the form of matching funds for presidential primary candidates.

This landmark case created the legal foundation for the Citizens United v. FEC decision issued 34 years later. The Supreme Court upheld contribution limits. However, it overturned spending limits (except for publicly financed presidential candidates). The decision said such restrictions “limit political expression at the core of our electoral process and of the First Amendment freedoms." The court upheld disclosure and recordkeeping requirements. In addition to striking down limits on candidate expenditures, the decision also invalidated limits on independent spending (spending not coordinated with a candidate) and on expenditures of candidates’ personal funds.

Congress responded to Buckley through the 1976 FECA amendments. The legislation reconstituted the Federal Election Commission (FEC), established new contribution limits, repealed expenditure limits (except for candidates who accepted public funding) and changed the way FEC commissioners are appointed.

The 1979 amendments simplified reporting requirements for some political committees and individuals and increased the public funding grants for presidential nominating conventions.

The law, commonly known as the McCain-Feingold Act, or BCRA, restricted so-called “soft money” donations — unlimited contributions to party organizations, often by labor unions and corporations, used for nebulous, unregulated “party building” activities — and tried to separate issue advocacy from candidate advocacy. The Act regulated issue advocacy by creating a new term in federal election law, “electioneering communications”— political advertisements that “refer” to a clearly identified federal candidate and are broadcast within 30 days of a primary or 60 days of a general election. Generally, the act prohibited unions and certain corporations from spending treasury funds for such “electioneering communications.”

BCRA faced major challenges from a host of litigants. McConnell v. FEC consolidated twelve lawsuits involving more than 80 plaintiffs. Mitch McConnell, a Republican U.S. senator from Kentucky and the current majority leader, has long been in favor of liberalizing restrictions on campaign contributions. The Supreme Court’s decision was considered a win for campaign reformers. A 5-to-4 majority upheld most of the law, including key provisions relating to political party soft money and electioneering communications. The court, however, invalidated its prohibition on contributions from minors age 17 and under.

In a significant setback for supporters of the Bipartisan Campaign Reform Act, the Supreme Court in a 5-4 decision concluded that restrictions on “electioneering” communications went too far. An electioneering communication is defined as a broadcast ad that is aired within 30 days of a primary or 60 days of a general election; names a candidate; and is targeted at voters. The law said corporate and labor money cannot be used to fund such advertisements. The court ruled that the provision was unconstitutional when it came to advertisements that did not expressly advocate for the election or defeat of a candidate.

In a case that continues to have an enormous impact on elections at all levels of government, the court reversed decades of decisions by allowing corporate and union dollars to pay for ads and other campaign materials that urge voters to vote for or against a candidate for office. The 5-4 decision affected what are known as “independent expenditures.” Such funds are used by an outside party to pay for materials that favor or oppose a candidate, but the spending must be “independent” — the outside party isn’t allowed to coordinate it with the candidate. The decision led to the creation of super PACs — which accept unlimited donations and use the funds mostly on political advertising — and “dark money” organizations, nonprofits that do essentially the same thing but are not required to reveal their donors.

While Citizens United set the stage for super PACs, the SpeechNow case, argued in the U.S. Court of Appeals for the D.C. Circuit, made them official. The decision struck down federal contribution limits to independent expenditure committees. It found that the high court’s analysis in Citizens United required the lower court to conclude that “the government has no anti-corruption interest in limiting contributions to an independent expenditure group.” The court, however, upheld the political committee disclosure requirements, so the donors to super PACs must be reported.

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.