This week, the U.S. Department of Justice initiated closing arguments in its historic case against Google , seeking to break up the world’s largest digital advertising ecosystem in a trial that could redefine the landscape of online commerce, publishing, and technology for years to come. How Did We Get Here?
Background and Ruling On September 22, 2025 , Judge Leonie Brinkema of the U.S. District Court for the Eastern District of Virginia began hearing arguments on remedies for Google’s unlawful monopoly in the ad
tech sector. Earlier this year, Judge Brinkema ruled that Google had illegally maintained a monopoly over the tools websites use to sell digital ad space, and the software that connects those publishers with advertisers looking to buy.
In her decision, Brinkema found that Google unlawfully tied together its publisher ad server (DFP) to its ad exchange (AdX), leveraging its dominance to stifle competition in display advertising.
“Google’s solutions were tailored, as law requires, to the technology in the case at hand and the complexity of the ad tech system,” said Karen Dunn, Google’s lawyer . The government disagreed: Nothing short of a structural divestment is sufficient to bring meaningful change, countered DOJ lawyer Julia Tarver Wood.
What’s at Stake? Billions, Innovation—and the Future of Digital Ads Google’s ad tech system controls an estimated 87% of the publisher-side ad serving market in the United States, allowing it to extract up to 20% fees on every auction , according to DOJ arguments. The digital ads industry is now valued at $305 billion annually…
