The big picture: A high-stakes legal battle over the future of Google’s advertising business is set to unfold this September, as the US Department of Justice pursues remedies that could reshape the digital ad ecosystem. As the trial approaches, both sides prepare for a legal showdown that could determine whether Google’s dominance in online ads remains intact or is fundamentally dismantled.

The US Department of Justice has confirmed its intention to pursue a breakup of Google’s advertising technology business, escalating the stakes in a high-profile antitrust battle. The DOJ is seeking a court order to force Google to divest key parts of its ad tech operations, including its ad exchange and publisher ad server, as part of efforts to restore competition in the digital advertising market.

This confirmation came during a hearing where US District Judge Leonie Brinkema set a trial date for September 22 to determine the appropriate remedies following last month’s ruling that Google illegally monopolized critical segments of online advertising technology.

The judge’s earlier decision found that Google unlawfully maintained monopoly power by tying its publisher ad server – software that helps websites manage and sell ad space – with its ad exchange, where advertisers bid for that space.

Google used to have 10 results meeting the searcher’s intent. Now, depending on the query, you’re seeing around 4-5 on-target results. Great job, Sundar, in boosting revenue while destroying the product silently. pic.twitter.com/rZ5yCjccjE

– Goog Enough (@Goog_Enough) April 25, 2025

Judge Brinkema emphasized that this conduct harmed publishers, competitors, and consumers by restricting competition and locking publishers into Google’s ecosystem. However, the court did not find Google to hold a monopoly over advertiser-facing tools, narrowing the scope of the ruling.

The DOJ’s proposed remedy is a phased approach beginning with Google providing real-time access to bidding data from its ad exchange to rival publisher ad servers. Ultimately, the government wants Google to sell off its ad exchange and publisher ad server businesses, a process DOJ attorney Julia Tarver Wood acknowledged could take several years. “Leaving Google with 90 percent of publishers dependent on them is, frankly, too dangerous,” Wood said.

Google vehemently opposes the breakup plan, arguing that the DOJ’s demands exceed the court’s findings and lack a legal basis. Karen Dunn, Google’s lead attorney, described the forced divestiture as “very likely completely impossible” and warned it would cause “serious complications,” including the loss of important privacy and security protections.

Dunn also questioned whether there are buyers that can run the complex ad tech systems outside of massive tech companies.

Instead, Google has proposed behavioral remedies, such as sharing a limited subset of ad data with competitors and ending certain anticompetitive pricing practices, including unified pricing.

The company also pledged not to reinstate discontinued tactics like “last look,” which previously allowed Google to outbid rivals at the last moment. To oversee compliance, Google suggested appointing a court monitor, but Judge Brinkema appeared skeptical of this approach during the hearing.

Lee-Anne Mulholland, Google’s vice president of regulatory affairs, criticized the DOJ’s breakup proposals as “go[ing] well beyond the Court’s findings, have no basis in law, and would harm publishers and advertisers.” She reiterated Google’s intent to appeal the ruling.

Also see: Google fights back: proposes to limit default search agreements, wants to avoid selling Chrome

The trial scheduled for September will mark a critical juncture in this legal saga, which follows similar antitrust challenges Google faces in its search business and the ownership of Chrome, the dominant browser in desktop computers and all Android phones.

Judge Amit Mehta is expected to rule on remedies in that case by August, with Google also confronting ongoing litigation over its Play Store policies. Together, these cases could lead to unprecedented structural changes for Google, potentially reshaping the digital economy.