Google is preparing for the ad tech trial of the century and the outcome could reshape how brands buy digital ads and publishers make money from the internet. At stake is the future of Google’s role in the online ad markets and whether it will have to spin off parts of its business that publishers use to manage their digital ad operations.

The outcome could usher in a new era of innovation or force Google to rethink its ad tech services for publishers if it can no longer drive much revenue from it because of new limits on its business, according to ad industry experts.

The U.S. Department of Justice brought the antitrust case against Google. The question at its core is whether Google used its dominant position to cement a monopoly in ad tech services for publishers. The case stems from Google’s acquisitions of advertising and publishing ad tech companies years ago, most notably DoubleClick, which it bought in 2008.

The question: “Does Google, by its nature, of owning the ad server and the exchange give themselves an unfair advantage,” said Harry Kargman, CEO of digital ad platform Kargo, “in terms of taking a ‘last look’ at available inventory to win [auctions] at a price that the rest of the industry would not be able to win at because of their position in the ecosystem.”

Kargman was not on the witness list for this case, but there are executives from all corners of the internet ad industry past and present. “It’s going to be fiery,” Kargman said.

Google will try to explain to Judge Leonie Brinkema—there will be no jury—the intricacies of this complex digital ad market. Google is set to argue that robust ad markets have evolved since it bought DoubleClick, and there are apps, social media, retail media networks and connected TV ad platforms that constitute a competitive playing field.

The DOJ already beat Google in a case in Washington this summer, where it argued Google ran a monopoly in search, supported by the fact it paid device makers, including Apple, to prefer its search engine. That case is still awaiting a decision on what to do about it, but it could spur some new dynamics in search markets. That ruling hangs over the upcoming case being tried in nearby Alexandria, Virginia, and shows anything can happen with sweeping ramifications for the ad world.

“It’s a foregone conclusion, they’re a monopoly in this case, because they lost the search case,” said one ad tech CEO who spoke with Ad Age on condition of anonymity. “If Google has a search monopoly and search data is used across its services [including advertising], therefore they have a monopoly here.”

Read about how the Google search ruling affects advertisers

The ad tech CEO, who is not a part of this case, said they were convinced the search ruling would affect how the next case gets decided. The ad tech CEO expected that Google would ultimately settle the case and spin off its publisher services and stop serving ads to third-party websites, which would represent a major disturbance in the online markets.

Google declined to comment for this story. The search giant is setting up a defense that there are larger digital ad markets than the display, open web advertising at the heart of this case. Also, Google is set to argue that its business model, servicing supply and demand sides of ad tech markets, is not unique.

The ad tech antitrust case will be closely watched by brands, publishers and ad tech players. Here is a primer on what to watch when the trial begins in U.S. District Court for the Eastern District of Virginia on Sept. 9.

How Google’s ad tech trial is shaping up

The trial is set to look back on Google’s hard-fought battle to lead digital advertising, to become the $240 billion-a-year ad business it is today. While some may not consider this a trial of the century-level case, it hinges on years of historical industry context and is set to have lasting ramifications.

Brian O’Kelley, CEO of Scope3 and former CEO of AppNexus, is on the witness list, and in the past was a strong critic of Google. AppNexus tried to mount a challenge to Google in internet advertising before selling to AT&T in 2018. AppNexus became Xandr, which is now owned by Microsoft. Google will likely argue that that ad platform also operates on both the buy and sell sides of internet advertising.

“Ten years ago, this would have been the trial of the century,” said O’Kelley. “The whole ad tech old guard is coming, yeah, because we’re the only ones who remember it.”

How Google built its ad tech edge

The DOJ argues that Google has a 90% share of the publisher ad-serving market after buying DoubleClick. Google turned DoubleClick for Publishers, the ad server, into Google Ads Manager. Google also runs ad exchange AdX, which has exclusive access to Google Ads, a lucrative source of advertising demand only available through Google. The DOJ alleges Google increased the price of ads, paid by the advertisers, to help grow the publisher side of its business—and is set to argue that Google’s practices eventually harmed publishers, too.

Read about how header bidding became central to this case

The case will also dive into some ad tech classics, such as the birth of header bidding. This type of auction was developed to circumvent Google’s dominant position in ad auctions. The DOJ is set to argue that Google used anticompetitive means to quash header bidding when it was developed more than a decade ago. Header bidding is a way for publishers to run auctions alongside Google’s auctions to get more independent bids.

How Google’s ad tech practices affect marketers

Google’s case has already been harmful to its relationship with marketers, who have seen the filings about how Google allegedly raised rates and other potentially damaging practices, advertising leaders said.

Brands won’t ditch Google by any means, but they would welcome more accountability, said Matt Voda, CEO of OptiMine, a performance marketing tech platform. “As a brand, you can’t just say we’re going to stop using Google. It’s such an important element of the digital marketing ecosystem, and so I think brands are watching [the trial], but they’re certainly not changing their behavior,” Voda said. “They’re not deallocating budgets … But I think brands would be happy if there are changes made. There will be, hopefully, better transparency, lower prices, more options in the market.”

The DOJ alleges Google used its position to coerce advertisers to use its ad tech products, including Google Ads and Display and Video 360 [DV360], its demand-side platform. For instance, there is no way for advertisers to buy YouTube ads without going through DV360.

How Google could defend its ad tech business

Google is setting the stage to argue that other ad tech participants have built products for the supply and sell sides, pointing to competitors such as Amazon, Xandr and Yahoo. Google’s pretrial inventory of evidence, which lists what type of documents it plans to present, shows a long litany of exhibits from other ad tech companies, possibly as an argument for how the ecosystem is vibrant.

The evidence list includes information from AdRoll, Adobe, Criteo, Colossus, Basis Technologies, Cognitiv, InMobi, Nexxen, PubMatic, Simpli.fi and The Trade Desk, among others.

In a blog post last year, Dan Taylor, Google’s VP of global ads, telegraphed the strategy to paint the new internet ad markets as competitive. “We are one of hundreds of companies that enable the placement of ads across the Internet,” Taylor wrote. “And it’s been well reported that competition is increasing as more and more companies enter and invest in building their advertising businesses.”

Read: The states’ case that gave way to the current DOJ action

What the Google ad tech evidence could show

However this case shakes out, if it goes to trial, there will be revelations about the intricacies of Google’s ad tech business. There will be a heavy focus on how Google runs internet ad auctions through its ad server, and whether that tilted the auction to favor its business.

The case already raised potentially troublesome behavior from Google, alleging it had internal projects to stifle innovations from rivals, such as header bidding, making it hard for publishers to get ad supply from other exchanges. The DOJ noted one Google project called “Jedi,” which was “designed to dampen competition and insulate Google’s ad exchange from vigorous competition.”

Undoubtedly, the trial will expose more of Google’s practices.

Ad tech star witnesses

The case features a VIP list of ad tech veterans expected to take the stand either live or via deposition. One of the star witnesses will be YouTube CEO Neal Mohan, who was the senior VP of strategy and product at DoubleClick before it was bought by Google. Mohan has been with Google ever since and has a deep understanding of the evolution of online digital ad markets.

Witnesses from major ad agencies will also have their say—executives from Omnicom’s OMD and GSD&M, WPP’s GroupM, The Goodway Group and others are expected to testify.

CEOs from ad tech companies that currently work and compete with Google are on the witness lists for both sides, including IndexExchange CEO Andrew Casale, PubMatic CEO Rajeev Goel and The Trade Desk Chief Revenue Officer Jed Dederick. For publishers, executives from BuzzFeed, The New York Times, Vox, and Gannett are coming.

How a Google loss could reshape the online ad biz

If Google loses or settles this case, ad tech markets will never be the same. And there could be unintended consequences, according to some ad leaders. Publishers may have to find a new ad server, for one, if Google is forced to spin out its business. For years, Google has basically offered its ad manager to publishers for free, because the value was in the interconnection with the ad exchange AdX, according to ad tech leaders.

“That might be the unintended consequence, that nobody is really thinking about,” Kargo’s Kargman said. “Google really loses money by operating the ad server on its own, and by blending the economics with AdX, it actually allows it to take that loss, because publishers are not really paying for that ad serving.”

“It could start charging them significantly more than they were paying today for use of the ad server,” Kargo said.

Another potential outcome is that Google may get out of the third-party ad sales business and retreat from serving ads to the open web, according to an ad tech executive who spoke on condition of anonymity. Instead, Google would focus on making as much money as possible from its main properties, such as search, Gmail and YouTube. That would represent the end of an era during which Google Ads funded millions of websites.

There could be a new proliferation of specialty ad servers, ad yield management platforms and demand side platforms rising to fill any void left by Google. Even Google, with this case behind it, could focus more on improving its services, no longer saddled by litigation.

“There’s no incentive to innovate when you have a monopoly, because they’ll just keep cashing the checks they’ve been making,” said Eric Wheeler, CEO of 33Across, a supply-side platform. “This could be a driver of next-level innovation, but it means they have to give up some of the cash cow.”