Political Action Committee (PAC): A political action committee is an organization that pools campaign contributions from members and donates those funds to campaign for or against candidates, ballot measures, or legislation.
Independent Expenditure: An independent expenditure is a political spending that is made without the cooperation or consent of a candidate's campaign.
Citizens United v. FEC:A landmark Supreme Court decision that ruled that the free speech clause of the First Amendment prohibits the government from restricting independent expenditures for political communications by corporations, labor unions, and other associations.