Trial Update, September 26, 2025: DOJ’s witnesses tell it like it is in a strong finish to week one

Day 5 of US v. Google adtech remedies began with a resolution on yesterday’s disputes about the trial exhibits regarding Google’s internal feasibility analysis. Both were admitted into evidence - one will remain sealed (PRX60) and one will be published, though it is heavily redacted (PRX50).

A reminder that we’re adding trial exhibits here on a rolling basis, and have also linked out to the DOJ and Google’s respective exhibits pages.

Mike Racic, President at Prebid.org

First up is Prebid.org’s Mike Racic. He explains Prebid is a not-for-profit (albeit tax-exemption is pending) organization, founded in 2017, that administers header bidding software. We talk about Prebid governance and funding. There is no fee for use of the technology. All revenue is derived from membership dues, though non-members can use the tech. Publishers play a flat fee, irrespective of size. Adtech companies pay based on revenue size. As an aside, I don’t love that size-based revenue model in such a concentrated market; but I also am thrilled to see this type of transparency from a trade group.

Half of the members are publishers, though about 90% of open-web publishers use prebid technology. We walk through the governance process for changes and updates. He explains the democratic process, where problems are raised, put to committee, tech specs are developed and issued for public comment, responses are provided on why certain comments were adopted or not, and ultimately the code is released.

Non-members can make suggestions too, in GitHub. That includes Google, who he says “can and do” make suggestions despite their persistent abstention. They have ten full-time employees, seven of which are engineers, along with a bunch of freelance engineers and about a hundred engineering volunteers.

In walking through the proposed remedies, Racic explains that GAM has blocked anyone else from running true Programmatic Guaranteed deals - you have to use AdX to do so. The buyer and seller also have to pay a fee, set by Google, in order to run these PG deals. If PG, PMP, and other similar deal types were to be excluded from “Qualifying Open-Web Display Transactions” as Google contemplates it, publishers would have no incentive to switch ad servers, he says. Publishers would still need to use two different systems. Prebid had software for PG deals, he notes, but sunsetted it since nobody could use it because of GAM’s restrictions.

DOJ preempts Google by having Racic explain a recent security incident where NPM (connected to GitHub) was hacked via a Phishing scam. Prebid team caught it within an hour, pushed a patch out shortly thereafter, and worked with HUMAN Security (the same HUMAN Security Google testified during liabilities to partnering with) to trace the hack and shared the intel with NPM.

Racic does a fantastic job making clear how tenable this open-sourcing of Final Auction Logic would be, and how absurd it is that Google includes PMP and PG deals in their definition of Direct transactions. Judge Brinkema has a lot of questions, and is clearly engaged. She asks how much effort it would take for Prebid to take on this open source Final Auction Logic work. He says that it depends on where the direct and indirect definitions net out, but if Google leans in, less than 6 months. Judge asks if that’s the case even given the size of the DfP business, and he explains that building a new ad server is a lot of work, but that is not what this is. Prebid already has auction logic, it’s just that GAM inserts itself at the end.

He doesn’t know exactly what would be involved because it depends on what will ultimately be deemed part of the Final Auction Logic, but auction logic itself is not incredibly difficult.  She asks if Google needs to sacrifice their source code, and he says that Prebid doesn’t need any of Google’s proprietary code that connects to Google tools - just the logic itself which Google would also be able to use; so no. Judge asks about whether AdX divestiture would impact any of this, and he says no. From Prebid’s perspective one more or one less SSP in the market doesn’t make a difference. If AdX sunsets in a couple of years, the impact is minimal, he notes. The Prebid Code of Conduct prohibits much of the same self-preferencing behavior the DOJ’s proposed remedies prohibit; so, all of the adtech companies that are Prebid members already agree to similar types of restrictions, DOJ points out.

Cross-examination by Bill Isaacson does not get very far. Again, there are improper attempts to impeach the witness where the witness did not actually contradict themselves. Racic’s matter-of-fact tone is funny juxtaposed next to Isaacson’s attempts at hyperbole.

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Dr. Goranka Bjedov, Technical Timeline Feasibility Expert

Dr. Bjedov is the expert that was the subject of a Google motion to exclude prior to the start of trial. It quickly becomes clear why they don’t want her to testify. She spent 5.5 years at Google, 8.5 years at Facebook as a Capacity and Performance Engineer. She was involved in major migrations like the Instagram acquisition, which moved onto the FB private cloud, and Facebook’s 2011 internal ad exchange re-architecture and redesign.

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She estimated up to 18 months for API creation, 24 months for open sourcing of Final Auction Logic, 18 months for AdX migration, and 24 months for DfP Remainder migration. The first three can occur in parallel - and while the DfP remainder migration technically could, too, that’s not what the DOJ’s proposed remedy entails. While some steps of the AdX and contingent DfP migrations would need to wait until a buyer is identified, the early steps - like Identification - can begin prior.  She outlines the number of engineers required at each step of the migration process. 12 engineers at Stage 1 (identification), 80 engineers at Stage 2 (separation), 40 at Stage 3 (testing), and 30 engineers at Stage 4 (deployment).  She’s asked if she was worried about finding 80 engineers for Stage 2. “It’s Google,” she responds, so no. As Judge Brinkema acknowledged following one of Google’s unnecessary objections, her timelines are “very consistent” with those of the Google witness, Tim Craycroft.

To that end, her testimony would have been fairly uneventful if not for her being absolutely hilarious the entire time. She remarks that one of Google’s experts, Jason Nieh, “certainly has more experience” being an expert witness, but he doesn’t have industry experience so projects that seem insurmountable to him from his Academic perch are simply the world she lived in. She said joining industry from academia was like Dorothy entering Oz with the massive amounts of money, resource, and scale. Another Google witness she is asked about, David Maymudes, provided a longer time estimate because he referenced, in part, migrations where they spent three years in meetings. “If you spend three years in meetings, it will take three years longer,” she notes.

We also got a peek at the unsealed exhibit ruled on this morning. It’s a clear mapping of the AdX divestiture and Open Source Auction from Google’s internal analysis. ‍

Phase 1: Sign agreement - transfer contracts, IP, etc.

Phase 2:  DfP Supports Prebid Server - AdX publishers transfer, Buyside support for gBid (bidding directly into the ad server, if we recall from yesterday),

Phase 3: Open Source Auction + Standard API - PCAS bids into Open Source Auction.

Cross-examination was just plain funny. At one point, Google’s Rhee asks if she can be assured that the product would be equivalent if she doesn’t know the buyer. Bjedov says that if there are reasonably competent engineers and they don’t spend three years in meetings, sure. She says she doesn’t know how to compute Rhee’s hypotheticals. No, she hasn’t “contemplated that someone would spend billions of dollars and flush it down the drain.”

What’s to come?

DOJ did not rest their case today. I left a bit early, but from what I understand:

Monday will start with Arnaud Creput, Equative CEO, before finishing up Dr. Goranka Bjedov. Tuesday we get Noam Wolf, Sr. Director of Engineering at Google - but a DOJ witness, followed by Rajeev Goel, CEO at Pubmatic. Then, DOJ will rest their case.