The Department of Justice and eight states have filed an antitrust lawsuit against Google. The states include California, Colorado, Connecticut, New Jersey, New York, Rhode Island, Tennessee and Virginia.
They claim the tech company has become a monopoly in the tech advertising space.
"Each time a threat has emerged, Google has used its market power in one or more of these ad tech tools to quash the threat," the lawsuit states. "The result: Google's plan for durable, industry-wide dominance has succeeded."
The lawsuit adds that Google controls technology used by "nearly every major website publisher to offer advertising space for sale," tools used by advertisers to buy advertising and "the largest ad exchange that matches publishers with advertisers"
The plaintiffs are asking the court to find that Google acted unlawfully to monopolize the online advertising market. They are seeking an unspecified sum in damages and requesting a jury trial.
Google has not publicly commented on the lawsuit.