The Federal Election Comision (FEC), established in 2002, is a government agency whose main function is to enforce campaign finance law in US federal elections.
The Bipartisan Campaign Reform Act (BCRA) is a federal law that amended the Federal Election Campaign Act of 1974. It regulates the financing of political campaigns.
Citizens United vs FEC was a legal case in which the US Supreme Court ruled that laws that prevented corporations or unions to use their funds for electioneering communications violated the First Amendment, which guarantees the freedom of speech.
The events reflect the process in which the government started developing tools in order to regulate the financing of political campaigns and how the system effectively solves issues regarding this subject, as political parties or organizations are abided by the Supreme Court in case they consider that the application of laws is unfair.