Google Ad Tech Remedies Trial: What Each Side Proposes and How to Prepare

Where the case stands

On September 22, the remedies phase of the Justice Department's ad tech case against Google began in federal court in Alexandria, Virginia. In April, Judge Leonie Brinkema ruled that Google unlawfully monopolized the open-web publisher ad server and ad exchange markets and illegally tied its exchange, AdX, to its publisher ad server, DoubleClick for Publishers (DFP). The question now is what Google must do about it.

This is the case most directly tied to how publishers sell display inventory. The outcome could reshape the tools many publishers use every day. It will also take time: after the testimony, the court still has to hear closing arguments and issue a decision, and an appeal is widely expected. Here is what each side is proposing, and why the overlap matters more than the differences.

What the DOJ wants

The government's proposal is structural and phased. As laid out in its filings and summarized in trade coverage, it includes:

• Making AdX's real-time bids available to rival publisher ad servers and tools, including through Prebid.
• Open-sourcing the final auction logic of Google's publisher ad server.
• Divesting AdX, overseen by a trustee, with restrictions on Google re-entering the exchange business.
• A path to divesting DFP as well, depending on how the earlier steps work.

The DOJ's argument is that Google has a history of working around conduct restrictions, so only separating the businesses will restore competition.

What Google proposes

Google's alternative, which it describes in a September 19 statement, centers on interoperability, including letting publishers use third-party tools to access AdX advertiser bids in real time. Its filed proposal also includes ending Unified Pricing Rules for open-web display and committing not to reintroduce first-look or last-look advantages in the open auction. Google argues the DOJ's remedies go beyond the court's liability findings and would make advertising more expensive and monetization harder.

The overlap is the part to plan for

The headlines focus on divestiture, but both proposals share a practical element: AdX demand becoming accessible from outside Google's own ad server, with Prebid named as a route. If that happens in any form, the quality of a publisher's independent auction becomes even more important, because more of the demand that matters would be competing inside it.

Similarly, both sides' positions point toward publishers regaining more flexibility over floors. Unified Pricing Rules have constrained how publishers can set different floors for different demand sources in Ad Manager. If those constraints loosen, floor strategy becomes a bigger lever, and a bigger responsibility.

How the options play out by publisher type

The effect of any remedy will depend on how a publisher sells today.

• Publishers running mostly AdX and Open Bidding with a light header bidding setup have the most to gain from cleaner competition, and the most operational work ahead if AdX demand moves into independent auctions. They should start strengthening their wrapper now rather than later.
• Publishers with mature Prebid setups already run a competitive auction outside Google. For them, the main question is how AdX demand would enter that auction, at what latency, and with what data attached.
• Publishers heavy on direct sales depend on the ad server for trafficking, pacing and reporting. For them, the biggest risk is disruption to the ad server itself, which is why the details of any DFP-related remedy matter more than the exchange question.

In every case, the operational cost of change falls on the publisher. Remedies designed to increase competition still require someone to configure, test and monitor the new setup.

What publishers should do now

1. Keep your wrapper current and clean. If AdX bids become available through Prebid, you will want a recent, well-maintained Prebid setup with sensible timeouts and a lean set of bidders, not an aging configuration nobody wants to touch.
2. Map your AdX dependency. Know what share of revenue flows through AdX and Open Bidding versus header bidding, by format, device and geography. You will need this to judge any change.
3. Build floor analytics. Start logging bid density and clearing prices by demand source now. If floor controls open up, the publishers with data ready will use them well. Those without will guess.
4. Review contracts and terms. Understand your current Ad Manager agreements, including any terms tied to specific features, so you can evaluate changes quickly.
5. Do not migrate on speculation. Replacing an ad server is a major project with real risk. Nothing ordered yet requires it, and any structural change would come with long transition periods.

What to watch next

Testimony will continue for several weeks, with closing arguments expected later in the fall. Watch for how Judge Brinkema responds to the feasibility of an AdX divestiture, which Google has argued is technically unworkable and the DOJ has argued is achievable. Also watch the European Commission, which fined Google €2.95 billion in early September and gave it 60 days to propose measures addressing conflicts of interest in its adtech stack. Remedies on both sides of the Atlantic could end up interacting.

The takeaway

The decision is months away and appeals will follow. But the direction is clear enough to act on: more interoperability between Google's demand and independent auctions, and potentially more publisher control over pricing. The practical preparation is the same under almost any outcome: a healthy header bidding setup, good data on where revenue comes from, and a clear floor strategy. That is the foundation HBDR works on with publishers regardless of how the court rules.