The federal government is suing automaker Volkswagen, alleging the company violated the Clean Air Act by using illegal devices to mask how much pollution its vehicles produced.
In September Volkswagen officials admitted that the company had installed software in some models that turned emission control systems on when a vehicle was being tested and then shut it off when a vehicle was on the road.
The U.S. Justice Department charges the system allowed Volkswagen vehicles to emit dangerous levels of air pollution.
The Justice Department is filing a lawsuit over the mater in the Eastern District of Michigan and will transfer the case to Northern California, where several class-action lawsuits against Volkswagen are pending.
The company could face more than $90 billion in fines.
Experts say it will be difficult for the automaker to defend itself, since it already admitted to cheating on emissions tests, and will instead likely try to negotiate a lower penalty.