Google Found to Hold Illegal Monopoly in Online Ad Tech, US Judge Rules

A U.S. federal judge has ruled that Google illegally maintained a monopoly over the digital advertising technology market, marking a significant win for antitrust regulators and potentially paving the way for major structural changes to the tech giant’s business.

The decision follows a lawsuit filed by the U.S. Department of Justice and 17 states, accusing Google of engaging in exclusionary practices to dominate key parts of the ad tech industry. The court found the company violated antitrust laws by controlling tools used by advertisers and publishers, as well as operating the exchange that facilitates transactions between them.

U.S. District Judge Leonie Brinkema wrote that Google had “wilfully engaged in a series of anticompetitive acts” that harmed publishers, distorted competition, and negatively affected consumers of online information.

Google plans to appeal the ruling. “Publishers have many options and they choose Google because our ad tech tools are simple, affordable and effective,” said Lee-Ann Mulholland, the company’s head of regulatory affairs. She emphasized that the court dismissed one of three claims, adding, “We won half of this case and we will appeal the other half.”

The decision is being seen as a landmark moment for antitrust enforcement in the tech sector. “It signals that not only are agencies willing to prosecute but also that judges are willing to enforce the law against big tech firms,” said Laura Phillips-Sawyer, a law professor at the University of Georgia.

Industry groups such as Digital Content Next welcomed the ruling. Its CEO, Jason Kint, accused Google of exploiting its dominance to favor its own platforms, “stifling innovation” and reducing revenues for online publishers.

While the ruling is unlikely to have an immediate impact on the online experience of internet users, it may alter the distribution of advertising revenue behind the scenes. Anupam Chander, a Georgetown University law professor, noted that while Google’s core role as an ad intermediary may remain intact, court-ordered structural changes could impact its financial performance.

The case now moves to a remedies phase, where more drastic measures could be considered—including the potential breakup of Google’s parent company, Alphabet. This could involve divesting assets such as its Chrome browser.

The ruling comes amid mounting global scrutiny of Google’s market practices. In a separate investigation last year, the UK’s Competition and Markets Authority also found the company engaged in anti-competitive behavior in the ad tech sector.