How did Citizens United v. Federal Election Commission affect corporate political advertising?

In the 2010 case Citizens United v. Federal Election Commission, the U.S. Supreme Court ruled that laws prohibiting corporations and unions from using their general treasury funds for independent "electioneering communications" violated the First Amendment guarantee of freedom of speech.1

By invalidating sections of the Bipartisan Campaign Reform Act and the Federal Election Campaign Act, the Court held that the government could not restrict independent political expenditures by corporations. The majority argued that such spending does not constitute quid pro quo corruption because it is not coordinated with candidates.12

This decision fundamentally altered the landscape of campaign finance by allowing corporations and unions to spend unlimited funds on independent political advertising. It directly facilitated the creation of Super PACs, which are permitted to make independent expenditures from general treasury funds to advocate for or against political candidates. While the ruling removed these spending bans, the Court upheld existing disclosure and identification requirements for such political communications.132