The American state of Alabama is suing BP and Transocean, the two companies it blames for the oil leak in the Gulf of Mexico, for damages.
Alabama is the first state to sue, since the Deepwater Horizon drilling rig, owned by Transocean and leased to BP, exploded on 20 April. The resulting oil leak took until 15 July to halt.
State attorney-general Troy King says BP has inflicted catastrophic harm.
However, the BBC reports he has not specified how much the state is seeking in damages.
The ABC reports more than 300 federal lawsuits have been filed since the disaster began.
The well has been plugged with mud and cement. Work on a relief stopped this week because of poor weather.
The relief well will allow engineers to pump in mud and cement from the bottom of the original well, permanently sealing it.