https://en.wikipedia.org/wiki/Citizens_United_v._FEC

Citizens United v. Federal Election Commission, No. 08-205, 558 U.S. 310 (2010), is a U.S. constitutional law and corporate law case dealing with the regulation of campaign spending by organizations. The United States Supreme Court held (5–4) that freedom of speech prohibited the government from restricting independent political expenditures by a nonprofit corporation. The principles articulated by the Supreme Court in the case have also been extended to for-profit corporations, labor unions and other associations.[2][3]

In the case, the conservative non-profit organization Citizens United wanted to air a film critical of Hillary Clinton and to advertise the film during television broadcasts, which was a violation of the 2002 Bipartisan Campaign Reform Act, commonly known as the McCain–Feingold Act or "BCRA".[4] Section 203 of BCRA defined an "electioneering communication" as a broadcast, cable, or satellite communication that mentioned a candidate within 60 days of a general election or 30 days of a primary, and prohibited such expenditures by corporations and unions. The United States District Court for the District of Columbia held that §203 of BCRA applied and prohibited Citizens United from advertising the film Hillary: The Movie in broadcasts or paying to have it shown on television within 30 days of the 2008 Democratic primaries.[1][5] The Supreme Court reversed this decision, striking down those provisions of BCRA that prohibited corporations (including nonprofit corporations) and unions from making independent expenditures and "electioneering communications".[4] The majority decision overruled Austin v. Michigan Chamber of Commerce (1990) and partially overruled McConnell v. Federal Election Commission (2003).[6] The Court, however, upheld requirements for public disclosure by sponsors of advertisements (BCRA §201 and §311). The case did not involve the federal ban on direct contributions from corporations or unions to candidate campaigns or political parties, which remain illegal in races for federal office.[7]