Ten US states, led by Texas, are charging Google, citing it for taking illegal steps to preserve its monopoly over the online advertising market.
The alleged moves include striking a deal with Facebook to control online advertising vendues, the states said.
This is the latest legal complaint facing the tech giant, which is under pressure from regulators globally.
Google dismissed the claims, saying it would be firmly protecting itself in court. We have invested in state-of-the-art ad tech services that help businesses and benefit consumers. Digital ad prices have fallen over the last decade. Ad tech fees are falling too. Google's ad tech fees are lower than the industry average, a company spokesperson said in response to Wednesday's lawsuit. These are the hallmarks of a highly competitive industry.
Facebook declined to comment.
The lawsuit targets Google's control of the online advertising market, which it says was fastened in 2008 with its purchase of DoubleClick, the main software that publishers use to sell online advertising.
Google's advertising sales stand for over 80% of its revenues.
The 10 states suing Google are Texas, Arkansas, Indiana, Kentucky, Missouri, Mississippi, South Dakota, North Dakota, Utah and Idaho, all of which have Republican prosecutors.
The states claim Google used its new role to benefit other parts of its business, for instance by forcing publishers to license its advertising servers. The lawsuit also says the firm took steps to secretly undermine innovations that were avoiding its fees.