14 October 2025

Inside final week of Google’s remedies trial: Trust, complexity, and the future of AdX

This article is not written, or presented as legal advice nor opinion. Readers should neither act, nor rely on opinion(s) in this article and linked materials without seeking legal counsel.

Louder’s opinions and perspectives are drawn from live trial commentary and reporting by sources including daily trial blogs, AP News, Reuters, and The Guardian.

In summary

• The two-week remedies trial in U.S. v. Google concluded on 3 October 2025 in Virginia.
• The DOJ pressed for AdX divestiture and non-discriminatory bidding, while Google countered with technical impossibility, innovation risk, and national security claims.
• Late testimony revealed that AdX separation is technically feasible, contradicting Google’s long-held stance, but likely to take several years.
• Judge Leonie Brinkema repeatedly highlighted that “trust, not just technology,” would determine the outcome.
• The trial wrapped on Friday 7 October with testimony from Matthew Wheatland of the Daily Mail, called by the DOJ as a rebuttal witness.
• Closing arguments are scheduled for 17 November 2025, with a ruling expected in early 2026.

The backdrop: Two weeks that could reshape ad tech

After a first week focused on technical feasibility and publisher testimony, the second and final week of U.S. v. Google shifted from theory to tension. Over ten days, Google’s engineers, economists, and executives faced cross-examination on what it would really take to separate its ad tech stack. Here’s how the remedies phase ended, and what it means for the open web.

For context, catch up on Louder’s earlier coverage:

• Pre-trial: The case against Google’s ad empire
• Week one: AdX divestiture takes centre stage

Trust on trial

The final week saw the DOJ sharpen its case around structural reform, while Google doubled down on a familiar defence: that unravelling its stack would be “technically unworkable” and “commercially catastrophic.”

Judge Brinkema, who has presided over the case for more than a year, made clear she was unconvinced by hand-waving or jargon.

“The issue isn’t what’s impossible,” she told Google’s counsel, “it’s what’s enforceable.”

Economic arguments: The “but-for” world

Google’s star economist, Dr. Andres Lerner, argued that even without the anticompetitive conduct proven in the liability phase, Google would still hold monopoly power “through pro-competitive means.” In his view, divesting AdX or imposing further restrictions would “punish success.”

The DOJ countered with a sharp analogy drawn from the International Salt precedent: when a monopoly is proven, courts don’t have to “leave every untraveled road open” for it to repeat old conduct by new means.

Judge Brinkema picked up on the contradiction: “If the purpose of remedies is to unfetter competition, how can we leave monopoly power intact?”

Lerner disagreed, saying his goal was to “unfetter conduct, not restructure success.”

The technical theatrics: Weaponised complexity

Google’s final witness, Jason Nieh, a technical feasibility expert, described divesting AdX or DFP as a “software engineering undertaking of unprecedented complexity.” He displayed dense dependency diagrams, likened the systems to “spaghetti,” and said the process could take “a decade or more.”

Commentators dubbed it “weaponised complexity,” a recurring theme across the trial.

The DOJ rebutted that complexity does not equal impossibility. Internal Google documents (Projects Sunday, Monday, and Cerulean) had already scoped divestiture scenarios, some concluding separation was technically feasible within four years.

Security and feasibility: Open source or open risk?

Google VP of Security Engineering Heather Adkins warned that open-sourcing Google’s “Final Auction Logic” could expose vulnerabilities. She invoked quantum computing, undersea cables, and nation-state hackers, a flourish that led commentators to note the “cyber-Armageddon” tone.

But DOJ lawyers pressed back: Google already open-sources Chromium and parts of Android, and itself relies on 19,000 open-source components. Judge Brinkema noted that “security concerns can’t conveniently begin and end where Google’s revenue does.”

The DOJ’s takeaway? Security issues were not a blocker, they were a distraction.

Publishers in focus: From Pubmatic to wikiHow to the Daily Mail

Pubmatic’s case for structural change

Pubmatic CEO Rajeev Goel returned to highlight persistent interoperability issues with Google’s systems, citing an eight-month-long “technical bug” that blocked publishers from monetising through Pubmatic’s Open Bidding integration while AdX remained unaffected.

Goel’s testimony underlined the DOJ’s argument: behavioural fixes aren’t enough if Google continues to “own both the pipes and the plumbing.”

wikiHow’s “real-world” anxiety

By contrast, Elizabeth Douglas, CEO of wikiHow, served as Google’s “small business” publisher witness. Her testimony humanised the stakes, and the fears, of disruption:

“Our business has to change or we’re going out of business,” and “there’s no SSP I trust as much as Google.”

Her comments resonated with smaller publishers reliant on Google for ad revenue, even as they acknowledged the need for reform.

The final word: Daily Mail’s rebuttal

The trial’s closing witness, Matthew Wheatland of the Daily Mail, was called by the DOJ to reinforce publisher concerns over transparency and control. His testimony revisited long-standing frustrations with Google’s auction opacity and take rates, a fitting bookend to two weeks dominated by the question of trust.

Judge Brinkema’s closing signals: Trust, not tech

Across her questions and interjections, Brinkema made one theme explicit: trust.
“The most important issue is whether the industry, and this court, can trust Google to play fair,” she said in the final week.

Observers read this as a signal that she may favour behavioural remedies (with strict monitoring) over immediate structural breakups, at least initially. But the tone also implied that if Google breaches new conditions, divestiture could be triggered later.

Likely outcomes: Reading the court’s hand

High likelihood:

• AdX required to bid into Prebid and other ad servers
• Five-year court monitoring period (Google had asked for three)
• Non-discriminatory bidding across AdWords and DV360
• Restrictions on AdWords routing directly into DFP

Possible but uncertain:

• Limits on Google’s use of first-party data for open-web display targeting
• Partial AdX divestiture or escrow model

Unlikely:

• Open-source auction logic, labelled “nice-to-have” rather than “need-to-have”
• DFP contingent divestiture, too broad, too far into the future

What’s at stake for the industry

Whatever the outcome, one fact is unambiguous: Google’s vertically integrated ad stack remains the nervous system of the open web. Any separation, technical or legal, will cause ripples across media buying, measurement, and publisher monetisation.

For advertisers and publishers, expect:

• Short-term fragmentation in measurement and data flows
• Higher operational costs as supply chains diversify
• Long-term transparency gains through open competition
• Greater scrutiny of self-preferencing across all major ad platforms

Or, as one expert summarised during cross-examination: “The question isn’t whether change is coming, it’s whether we’ll control the change, or be controlled by it.”

Louder’s recommendation

At Louder, we see the DOJ v. Google remedies trial as a turning point for marketers and publishers navigating the next era of ad tech.

• Invest in owned interoperability. Adopt standards (like Prebid and IAB Tech Lab frameworks) that ensure future flexibility.
• Double down on technology ownership and first-party data. Privacy-compliant signal strength will only grow in value.
• Plan for disruption. Model operational workflows that work seamlessly across teams, not confined by siloed measurement systems, ad servers, or DSPs.
• Monitor regulatory echoes. Australia and the EU are watching closely; similar competition or privacy enforcement is likely.

So, what’s next?

Closing arguments are scheduled for 17 November 2025, with a ruling expected in early 2026.

Whether Judge Brinkema orders structural reform or opts for enhanced oversight, one outcome is already clear: the era of automatic trust in Google’s ad ecosystem is over.

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