District Attorney Tony Rackauckas said at a news conference that his office has the right to bring consumer protective action on behalf of county residents.
"We need to make sure that when Toyota says, 'Oh, what a feeling' and 'Moving forward' that they are talking about great cars," Rackauckas said, referring to the company's slogans.
Toyota spokesman Mike Michels said he had no comment because the company hasn't been served with the lawsuit.
Orange County's lawsuit accuses Toyota of using deceptive business practices to become the world's top automaker. The suit seeks civil penalties of $2,500 per violation under the Unfair Business Practices Act, along with the recovery of attorney fees and investigative costs.
"We demand to know: Did Toyota, in their relentless pursuit to become the No. 1 carmaker in the United States, put profits over people?" Rackauckas asked.
The district attorney's office hired a private law firm with expertise in consumer safety liability cases to help with the case.
Toyota has recalled more than 6 million vehicles in the United States because of acceleration problems in multiple models and braking issues in the Prius hybrid. Regulators have linked 52 deaths to crashes allegedly caused by accelerator problems.
At least 89 class-action lawsuits have been filed against the Japanese automaker, which could cost the company $3 billion or more.
Toyota's U.S. shares fell 12 cents to $76.82 Friday.
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