Google fights DOJ push to break up ad tech business as antitrust trial opens

Alphabet’s Google is back in court, facing a U.S. Department of Justice (DOJ) bid to force it to divest parts of its online advertising empire. The antitrust trial, which opened Monday in Alexandria, Virginia, could reshape the digital ad market if the government succeeds.

The DOJ and a coalition of states want Google to sell its ad exchange AdX, which charges publishers a 20% fee to auction ads in real time, and to make the auction’s decision-making mechanism open source. Prosecutors argue that only structural remedies like divestiture can address Google’s illegal monopolization, after U.S. District Judge Leonie Brinkema ruled earlier this year that Google unlawfully tied AdX to its publisher ad server.

“Leaving Google with the motive and the means to recreate that tie is simply too great a risk,” DOJ attorney Julia Tarver Wood said in opening statements.

Google’s lawyer Karen Dunn pushed back, calling the proposals “radical and reckless,” claiming they would harm competition by giving regulators “broad and unparalleled power” over a major tech platform. Instead, Google has offered policy changes that would make it easier for publishers to work with rivals — but the DOJ insists such tweaks are insufficient.

The trial follows a recent DOJ loss in a separate search monopoly case, where a Washington, D.C. judge refused to impose most of the government’s remedies. But prosecutors argue this case is different, since ad tech is the monopoly itself rather than just a distribution method.

Industry stakeholders are closely watching the outcome. Grant Whitmore of Advance Local, which runs local news outlets in eight states, testified that Google’s control of advertiser tools, publisher tools, and the AdX exchange “offers a lot of opportunities for Google to continue to put their thumb on the scale.” He said Google should also be forced to sell its publisher ad server.

Google has previously floated selling AdX to settle an EU investigation, according to Reuters, and internal documents from those talks may surface during this trial.

The case is part of a broader bipartisan effort to curb Big Tech power, with ongoing actions against Meta, Amazon, and Apple. The stakes are high: a forced breakup of Google’s ad tech stack would mark one of the most significant antitrust interventions in the digital economy’s history.