In a landmark decision, a U.S. federal judge has ruled that Google, a subsidiary of Alphabet Inc., illegally monopolized key sectors of the online advertising technology market. The ruling marks a significant setback for the tech giant, which has long dominated the digital advertising landscape. The court found that Google’s practices in the publisher ad server and ad exchange markets violated Sections 1 and 2 of the Sherman Antitrust Act. However, the court dismissed claims regarding Google’s dominance in the advertiser ad network market.
The antitrust lawsuit, filed by the U.S. Department of Justice (DOJ) and 17 state attorneys general, accused Google of engaging in anticompetitive behavior to maintain its dominance in the digital advertising ecosystem. Specifically, the plaintiffs alleged that Google tied its publisher ad server (DoubleClick for Publishers) with its ad exchange (AdX), effectively forcing publishers to use both services and stifling competition.
The case, United States v. Google LLC, was filed in the U.S. District Court for the Eastern District of Virginia. The trial began on September 9, 2024, and concluded on September 27, with closing arguments delivered on November 25, 2024.Judge Leonie Brinkema presided over the case and issued the ruling on April 17, 2025.
Judge Brinkema’s 115-page ruling concluded that Google willfully engaged in a series of anticompetitive acts to acquire and maintain monopoly power in the publisher ad server and ad exchange markets for open-web display advertising. The court found that for over a decade, Google improperly tied its publisher ad server and ad exchange through policies and technology, harming publishers and web users.
However, the court dismissed the DOJ’s claim that Google also monopolized the advertiser ad network market, stating that the plaintiffs failed to prove that Google’s conduct in this area violated antitrust laws.
In response to the ruling, Google’s Vice President of Regulatory Affairs, Lee-Anne Mulholland, stated that the company would appeal the parts of the ruling it lost. She emphasized that the court found Google’s advertiser tools and acquisitions, such as DoubleClick, did not harm competition. Mulholland asserted that publishers have many options and choose Google because its ad tech tools are simple, affordable, and effective.
The court’s decision opens the door for the DOJ to seek structural remedies, including potentially breaking up Google’s advertising technology operations. Such remedies could involve forcing Google to divest key assets like Google Ad Manager or AdX. The outcome of the remedies phase will significantly impact the digital advertising industry, potentially creating opportunities for competitors and altering the dynamics of online ad auctions.
This ruling marks the second major antitrust loss for Google in recent months. In August 2024, a different court ruled that Google abused its dominance in the online search market. These cases are part of a broader effort by the U.S. government to rein in the power of Big Tech companies and promote competition in digital markets.
The partial loss in the advertising tech antitrust case represents a significant challenge for Google as it navigates increased regulatory scrutiny. The forthcoming remedies phase will determine the extent to which Google’s ad tech business may be restructured. As the digital advertising landscape evolves, the outcomes of such legal battles will shape the future of competition and innovation in the industry.
