Twitter in the US must pay a $150m (£119m) fine after law enforcement officials accused it of illegally using users' data to help sell targeted ads.
The Federal Trade Commission (FTC) and the Department of Justice say Twitter violated an agreement it had with regulators, court documents showed.
Federal investigators say the social media company broke those rules.
Twitter was fined £400,000 in December 2020 for breaking Europe's GDPR data privacy rules.
The FTC is an independent agency of the US government whose mission is the enforcement of anti-trust law and the promotion of consumer protection.
It accuses Twitter of breaching a 2011 FTC order that explicitly prohibited the company from misrepresenting its privacy and security practices.