California will join the US government and 11 other states in bringing lawsuits against Google for abusing its market dominance, the state's top prosecutor said Friday.
"Google's market dominance leaves consumers and small businesses with little choice when it comes to internet search engines," Attorney General Xavier Becerra said in a statement.
"By using exclusionary agreements to dominate the market, Google has stifled competition and rigged the advertising market."
The US Justice Department and 11 states in October brought a civil case against Google for pursuing an illegal monopoly in its search functions and in its advertising research services.
Google, founded in 1998 and headquartered in California, has often been accused of abusing its power to exclude competitors.
It is the default search engine on many devices, and its Chrome web browser and mobile operating system Android dominate the market.
The US Justice Department also accuses it of forcing consumers and advertisers to use its services on Android devices on apps that cannot be deleted, such as Google Maps.
On Wednesday the Federal Trade Commission (FTC) and prosecutors representing 48 states and territories also announced they had filed a complaint against Facebook for abusing its market dominance.