Citizens United v. FEC (2010) was a 5–4 Supreme Court decision holding that the First Amendment bars limits on independent political spending by corporations, unions, and nonprofits.
The ruling did not strike down limits on direct donations to candidates; those caps remain in place. It struck down limits on independent expenditures by outside groups.
Outside spending in federal elections grew from roughly $338 million in 2008 to over $2.7 billion in 2020, according to OpenSecrets data.
Supporters frame the ruling as a First Amendment protection: political speech can't be limited based on the identity of the speaker. Critics argue it has shifted political influence toward wealthy donors and dark-money networks.
Overturning the decision would require either a constitutional amendment, a future Court reversing precedent, or — narrowly — new disclosure-based legislation. None have advanced in Congress.