Google's advertising business, which generates key revenue for the tech giant, is an illegal monopoly, a federal judge ruled on Thursday. In the ruling, US District Judge Leonie Brinkema wrote that Google violated Section 2 of the Sherman Act,

Judge Brinkema’s ruling found Google “liable under Sections 1 and 2 of the Sherman Act” for its monopolistic behaviors in the ad tech tool and exchange businesses, but the judge did dismiss another charge that Google had operated a monopoly in ad networks.

Google illegally acted to preserve “monopoly power” in the digital ad-tech business, a federal judge ruled Thursday. It’s the second antitrust case brought by the U.S. government that has gone against the internet giant in the past year.