Everything you need to know about the closing stages of Google’s ad tech antitrust trial

As the case moves into the remedies phase, the question isn’t just what gets unwound. It’s whether it still matters. Google has already managed the quiet decline of its ad tech business, shedding market share in the process. And the open web, which it once powered, is splintering into retail media, walled gardens, and AI-native interfaces. The next version of the internet isn’t waiting for a court order. 

Whatever remedy emerges, behavioral or structural, the outcome may end up being less of a reckoning and more of a temporary lift: a float for an ad-funded internet still trying to figure out what comes next. Here’s what to know as the industry braces for the fallout. 

What now?

We’ve now entered the remedies phase of the Department of Justice’s antitrust case against Google’s ad tech empire. Back in the spring, Judge Brinkema sided with the DOJ, ruling that Google held illegal monopolies in the open web display publisher ad server and ad exchange marketplaces, and that it unlawfully tied those products together. Today, the court is back in session, with the outcome determining how a vast swathe of the open internet will be funded in the coming years.

After Google and the DOJ make their cases, Justice Brinkema will make a decision that does the following four things:

• Free the market from anticompetitive behavior, 
• Unwind Google’s illegal AdX and DFP monopolies  
• Deny the company any continued benefits from that dominance 
• Block future attempts to rebuild the same empire in a different guise 

The DOJ’s proposals

The DOJ is targeting the heart of Google’s ad tech stack — AdX. Its argument is simple: the ad exchange, which sits at the center of programmatic trading and fuels much of the open web, is the source of Google’s market power. Strip that out, and the rest starts to fall. The DOJ, however, is not asking for a divestiture of DFP. It doesn’t have to because DFP and AdX are so deeply intertwined; pulling the exchange apart would, by design, weaken the ad server. Without privileged access to Google’s dominant exchange, the ad server loses its edge, making it easier for publishers to walk away and breaking the feedback loop that entrenches Google.

In parallel, the DOJ wants Google auction logic – the decision-making engine behind who wins ad placements – to be open-sourced. That move, although technical on the surface, is designed to level the playing field and give competing ad tech providers a genuine opportunity on the publisher side. If it doesn’t, then the DOJ wants the court to revisit the judge’s decision in two years and consider spinning off the ad exchange completely.  

Witnesses 

A cross-section of the ad ecosystem is headed to the stand: ad tech operators, publishers, agency execs, and advertisers – each offering a window into how Google’s monopoly, and what might unravel if that grip is loosened. Below is a list of some of the more eminent names among them. 

DOJ’s lineup

• Matthew Wheatland, DailyMail.com’s chief digital officer
• Stephanie Layser, head of publisher ad tech solutions, AWS (formerly News Corp.) 
• Grant Whitmore, Advance Local, CEO
• Rajeev Goel, CEO, PubMatic 
• Andrew Casale, CEO, Index Exchange 
• Arnaud Créput, Equativ, CEO 

Google’s lineup 

• Jason Nieh, Professor of computer science, Columbia University
• Heather Adkins, vp security engineering, Google 
• Sam Greenfield, senior staff software engineer, Google 
• George Levitte, director, product management (AdX/DFP), Google 
• Jed Dederick, The Trade Desk, CRO  

Google’s proposals

Google has submitted remedies, arguing to the court that the DOJ’s proposals are excessive, instead asking the judge to focus on technical integrations to enhance publisher access to ad demand, which it claims would address market requirements. 

Google believes the behavioral remedies will sufficiently address the conduct that the court found to be monopolistic in April 2025 – intuitively, it is arguing against a divestiture. Broadly, its proposals can be categorized into three categories, see below. 

• Deeper interoperability with rival ad servers 
• Deprecate unified pricing rules 
• Agreeing not to use ‘first look’ and ‘last look’for open web ads

According to Google’s assessment, a technical integration can open up access, allowing publishers to receive Google’s demand, i.e., AdX, via third-party ad servers, in real-time. 

Similarly, it proposes an integration (built alongside Prebid) that would allow publishers to gain direct access to AdX demand in real-time via header bidding. Furthermore, Google proposes that publishers can (if they choose to) place Prebid’s technology between DFP and AdX, thus ensuring that there isn’t a single Google-owned point of connecting between the publisher ad server and the ad exchange. 

Additionally, the commitment not to re-establish unified pricing rules for open web display ads will allow publishers to exercise a preference for which ad exchanges to use, other than AdX, per Google.

Google’s rationale

Per Google, the DOJ’s remedies lack a legal basis, as the court found no unlawful acquisition; hence, divestiture would be disproportionate, arguing that such a path would entrench court oversight for a decade, halt innovation, and thus harm competition. Deeper interoperability with rival ad servers will address the ruling that publishers were discouraged from switching away from DFP.

Judge Amit Mehta’s separate antitrust ruling, which meant that Google didn’t have to divest Android or Chrome, along with the disruption of AI, will cast a shadow over this case, dynamics that are likely to manage the expectations of many media industry observers.  

According to Arielle Garcia, a former ad-industry insider and trial commentator at CheckMyAds, the Sept. 2 ruling is the elephant in the room. “The primary purpose of Google’s recent legal framework brief is to subtly pressure the court to fall in line with Judge Mehta’s refusal to order divestiture, and to keep remedies really narrow,” she adds.  

Meanwhile, in a prepared statement, Lee-Anne Mulholland, vp, regulatory affairs, Google, says, “Breaking apart integrated tools would make it harder for publishers to monetize their content and more expensive for advertisers to reach new customers, disproportionately hurting the small businesses who choose to use Google’s tools to grow.”

While Judge Leonie Brinkema will have a thorough understanding of the distinction between the search and display advertising sectors by now, the ruling in the search antitrust case will have a bearing, with most observers anticipating a higher likelihood of divestiture in the ad tech proceedings.  

And while rival ad exchanges Magnite, OpenX, and PubMatic have all filed lawsuits seeking damages related to the April 17 rulings, Google has signaled its intention to challenge both of those losses as well as the guilty search verdict. Industry observers should note that this one is far from over.    

Estimated timelines

• Remedies trial testimony: September 22-30, possibly into early October
• Post-trial briefing: ~30 days after close of evidence – late October or early November
• Closing arguments: ~2 weeks after briefs – mid–to-late November
• Judge’s ruling: No set date; likely in 2026, not 2025 – say experts