A major legal showdown is set to unfold this September that could reshape the way digital advertising works — and potentially mark one of the biggest antitrust victories in U.S. history. The U.S. Department of Justice (DOJ) is pressing for the breakup of Google’s advertising business after a court ruled that the tech giant unlawfully used its dominance to control the online ad market.
The trial, scheduled for September 22, follows a ruling by U.S. District Judge Leonie Brinkema, who found that Google maintained an illegal monopoly by tying its advertising products together in ways that harmed both competitors and publishers. Now, the court will decide what consequences Google should face — and the DOJ is pushing for one of the most aggressive outcomes: splitting off the core parts of Google’s ad tech business.
DOJ Demands Google Give Up Its Ad Tech Crown Jewels
At the heart of the DOJ’s case are two key tools: Google’s ad exchange, where advertisers bid to place ads, and its publisher ad server, which helps websites manage that ad space. The DOJ argues that controlling both systems allows Google to manipulate auctions and lock out competition.
DOJ attorney Julia Tarver Wood described Google’s hold on the digital ad supply chain as dangerously dominant. “Leaving Google with 90% of publishers still dependent on them is, frankly, too dangerous,” she said during a recent hearing. The DOJ’s proposed plan starts with forcing Google to share more real-time bidding data with rivals, eventually culminating in a full divestiture of those ad tech operations.
This structural remedy, officials say, is essential to restore competition and break what they see as Google’s chokehold on how ads are bought and sold online.
Judge Previously Found Google Crossed the Line
Last month, Judge Brinkema ruled that Google crossed legal boundaries by linking its ad server and exchange products in a way that hurt market competition. While she did not find that Google had monopolized the tools used by advertisers, she made it clear that the company’s behavior harmed the broader ecosystem — especially publishers and smaller competitors trying to break in.
According to the court, this behavior limited innovation, trapped publishers in Google’s ad system, and reduced options for advertisers. Brinkema signaled that she was open to considering meaningful remedies — including a breakup.
Google Pushes Back: Breakup Would Be “Impossible”
Google, for its part, is firmly opposed to the idea of being broken up. The company says the DOJ’s proposed remedy is excessive and not supported by the court’s ruling. Karen Dunn, Google’s lead lawyer, argued that a forced divestiture would be “very likely completely impossible” to execute and would jeopardize privacy, security, and the effectiveness of online advertising.
She also questioned whether there were any suitable buyers capable of running the complex ad tech systems currently operated by Google, suggesting that a breakup could lead to more chaos than competition.
Google’s Offer: Behavioral Fixes and a Monitor
Rather than selling off its ad business, Google has proposed what it calls “behavioral remedies.” These include ending certain pricing practices, committing not to bring back discontinued tactics like “last look” bidding advantages, and sharing limited data with competitors. Google also floated the idea of appointing an independent monitor to ensure compliance.
But Judge Brinkema didn’t seem convinced during the hearing. She questioned whether oversight alone could prevent Google from continuing to abuse its market power.
Google Plans to Appeal, DOJ Holds Firm
As the legal process moves forward, Google has made it clear that it intends to fight. Lee-Anne Mulholland, the company’s vice president of regulatory affairs, slammed the DOJ’s approach as going “well beyond the court’s findings” and warned that forcing a breakup could hurt both advertisers and publishers.
Google has signaled plans to appeal, a move that could stretch the timeline for any significant change by years.
The Bigger Picture: Antitrust Pressure Builds
The ad tech case isn’t the only antitrust battle Google is facing. Another trial over its dominance in search and Chrome — the most widely used browser — is also underway, with a decision expected by August. Meanwhile, Google is also being challenged over its control of the Google Play Store, with potential consequences for its mobile app empire.
Together, these cases reflect growing momentum among regulators to rein in Big Tech. If courts side with the DOJ across multiple fronts, Google could face sweeping structural reforms that would impact the digital economy for years to come.
