U.S. District Judge Leonie Brinkema ruled that Google broke the law by unfairly dominating two major parts of the online advertising world:

• The publisher ad server market
• The ad exchange market

The 115-page decision says Google broke a key antitrust law (the Sherman Act, Section 2) by purposely gaining and keeping too much control over these areas.

The court also found that Google wrongly forced companies to use its ad server (called DFP) and its ad exchange (called AdX) together, instead of letting them choose each service separately.

Judge Brinkema explained this clearly in her ruling:

“Plaintiffs have proven that Google possesses monopoly power in the publisher ad server for open-web display advertising market. Google’s publisher ad server DFP has a durable and ‘predominant share of the market’ that is protected by high barriers both to entry and expansion.”

How Much Control Google Had Over the Ad Industry

The court found that between 2018 and 2022, Google controlled about 91% of the global market for software that helps websites manage and show ads.

In the area where ads are automatically bought and sold (called an ad exchange), Google’s platform AdX handled 54% to 65% of all ad sales—making it nearly nine times bigger than the next largest competitor.

The judge also pointed out that Google charged much higher fees than others. While most platforms took about 10%, Google kept 20% for over a decade.

The ruling states:

“Google’s ability to maintain AdX’s 20% take rate under these market conditions is further direct evidence of the firm’s sustained and substantial power.”

Illegal Tying of Services Found
A big part of the court’s decision focused on how Google linked two of its ad products in a way that gave it an unfair advantage.
The court said Google made publishers use its ad server (DFP) if they wanted access to real-time bidding from AdWords advertisers—a key feature of its ad exchange (AdX).
Judge Brinkema supported this by quoting messages from inside Google that showed the company knew this setup gave it more control over the market:

“By tying DFP to AdX, Google took advantage of its ‘owning the platform, the exchange, and a huge network’ of advertising demand.”

This was compared to a major bank like Goldman Sachs or Citibank owning the New York Stock Exchange.

Background of the Case and State Support

The Department of Justice filed the lawsuit against Google in January 2023, along with eight states. Later, nine more states joined, making it a total of 17 states challenging Google’s actions.

Michigan Attorney General Dana Nessel explained why the states got involved:

“Google’s power in online advertising has pushed smaller companies out or made them depend on Google’s system.”

Google has denied doing anything wrong. Dan Taylor, Vice President of Global Ads, said the lawsuit would “undo years of progress and hurt the whole advertising industry.”

What It Means for Digital Marketers

This ruling could bring changes to digital marketing:

• For publishers: If Google has to change how it runs its ad business, publishers might get more control and possibly earn more money.
• For advertisers: There may be clearer pricing and lower costs if changes are made to how Google’s ad system works.
• For marketing agencies: It might become more important to use different ad platforms, not just Google.

What’s Next?

Judge Brinkema hasn’t decided what penalties Google will face. The court will soon schedule more steps to figure out what actions to take.

One possible outcome is that Google could be forced to sell parts of its ad business. This would be a big change in the online ad world.

The ruling shows that changes could be coming for anyone who depends on Google’s all-in-one ad system.

Google plans to appeal the ruling, which means the legal fight could last for years.

From Google’s newsroom on X:

“We won half of this case and we will appeal the other half. The Court found that our advertiser tools and our purchases, like DoubleClick, don’t hurt competition. We disagree with the Court’s decision about our publisher tools. Publishers have many choices and they…”

— News from Google (@NewsFromGoogle) April 17, 2025”