Returning to the World of Digital Ads: A Primer on the Google – DOJ Case Ahead of the Remedies Phase
Next week, on September 22, the remedies phase of the Department of Justice’s (DOJ) lawsuit against Google’s digital advertising services (AdTech) is set to begin. Before proceedings get underway, it is worth revisiting the current state of the case.
In 2023, the DOJ, along with eight state attorneys general, filed a lawsuit against Google, claiming that Google illegally monopolized parts of the digital advertising market. In particular, DOJ claimed that:
- Google monopolized the publisher ad server market;
- Google monopolized or attempted to monopolize the ad exchange market;
- Google monopolized the advertiser ad network market; and
- Google unlawfully tied its ad exchange to its publisher ad server.
To prove liability, the DOJ needed to show that (1) Google has monopoly power in the relevant markets identified in the claims, and that (2) Google had illegally maintained the alleged monopoly and that its conduct had resulted in the exclusion of its competitors.
The DOJ’s arguments rested heavily on its definition of“relevant markets.” As such, the definitions were drawn narrowly around “open web display ads” and “advertiser ad networks,” while excluding other ways ads are bought and sold, such as through apps, videos, and elsewhere. This approach overlooks the fact that the same underlying ad tech can operate across various environments.
Drawing artificial lines around “open web display ads” does not reflect the reality of how businesses advertise and how advertising markets work. As CCIA stated at the time of the DOJ’s filing, “The government’s contention that digital ads aren’t in competition with print, broadcast, and outdoor advertising defies reason.” As a previous post noted when the case began, the DOJ’s position had significant shortcomings.
In early 2025, U.S. District Judge Leonie Brinkema ruled that Google was liable for “willfully acquiring and maintaining monopoly power” in markets for publisher ad servers and the market for ad exchanges, which help connect companies seeking to advertise with sellers of advertiser space.
Importantly, the ruling made clear that the DOJ “failed to prove that there is a relevant market for open-web display advertiser ad networks.” Additionally, Judge Brinkema’s decision reaffirmed the Trinko decision, rejecting the notion that Google had a “duty to deal” with competitors seeking access to the company’s customer lists.
As previously discussed, advertising is a fiercely competitive, multi-sided market where businesses have more options than ever to reach consumers, from search and social to video, apps, and beyond. Careful consideration of all aspects of a market definition is essential to assessing whether the antitrust agency needs to intervene to correct potentially anticompetitive behavior. The interconnected nature of this market and the importance of a proper market definition are key weaknesses of the DOJ’s arguments.
As the remedies proceedings begin next week, the court must consider the digital advertising market with a more holistic approach to ensure that any ruling will take into account the complex nature of this market. Market realities matter, and remedies must reflect the competitive and dynamic nature of the advertising industry.
The court’s ruling will be closely watched by businesses and consumers alike. Overly broad remedies could disrupt the balance of the digital advertising ecosystem, potentially harming competition and innovation, and limiting the options available to publishers, and users. The stakes are high, and the outcome of this case may shape the future of the online advertising industry for years to come.
