An oil drilling services company filed a lawsuit against BP Monday, seeking compensation for the loss of business it says resulted from the Deepwater Horizon oil spill.

Crescent Drilling and Production Inc., which provides engineering services for companies drilling for oil both on and offshore in the Gulf of Mexico, alleges that because of the moratorium imposed on new Gulf leases after the spill, Crescent experienced a loss of revenue that it wants BP to be held accountable for. The company claims that under the Oil Pollution Act, BP is responsible for all damages that result from the oil spill, including Crescent’s lost income and business opportunity.

“As direct and foreseeable response to the Oil Spill, and the foreseeable governmental response, including the Moratoria imposed in direct response to the Oil Spill, Crescent sustained a loss in business as various projects were suspended or cancelled by Crescent’s drilling operator clients,” the lawsuit reads.

Crescent’s lawsuit comes less than a week before the fourth anniversary of the Deepwater Horizon disaster, which killed 11 people and spilled 210 million gallons of oil into the Gulf of Mexico. BP has been no stranger to lawsuits since the spill: last month, an appeals court ruled that the oil company must reimburse Gulf businesses that claim damages, even if they don’t submit proof that their losses came from the spill. BP had claimed in 2012 that it was suffering major losses by having to pay hundreds of millions of dollars to businesses that exaggerated or invented losses from the spill. And in January, a judge ruled that two BP rig supervisors must face involuntary manslaughter charges over the deaths of the 11 rig workers.

Four years after the spill, BP’s impacts are still being felt in the Gulf ecosystem. A report published last week by the National Wildlife Federation outlined how 14 Gulf species, including bottlenose dolphins and bluefin tuna, are still struggling in the aftermath of the spill — a report that BP disputes. The spill also killed off marsh grass and mangroves along the Louisiana coast, which has caused erosion to speed up in some areas, leading to losses in habitat for birds and other wildlife.

And despite the time that’s passed since the April 20 disaster, the U.S. hasn’t tightened safety regulations on blowout preventers, the piece of equipment that failed on the Deepwater Horizon operation four years ago. In April 2011, the Department of Interior promised to propose new blowout preventer rules by the end of the year, but the agency missed that deadline and the two other deadlines it subsequently set for the rule proposals. The Interior Department’s website shows that the rule was scheduled to be proposed in March 2014, but the agency has yet to formally do so. Rules on criteria for well design are scheduled to come out in June, and regulations for Arctic drilling were supposed to come out in February but have yet to be proposed.