Three companies shared legal responsibility for the Deepwater Horizon disaster: BP, Transocean, and Halliburton. In a landmark 2014 ruling, a federal judge found BP grossly negligent and assigned it 67 percent of the fault. Transocean, which owned and operated the drilling rig, bore 30 percent. Halliburton, which performed the cement work on the well, was assigned 3 percent. A weak federal regulator also played a background role by failing to enforce adequate oversight of deepwater drilling.
BP: The Operator Calling the Shots
BP held the lease on the Macondo well, located about 40 miles off the Louisiana coast in roughly 5,000 feet of water. As the well operator, BP made the key engineering and scheduling decisions throughout the project. The federal court’s finding of “gross negligence” is a legal term that goes beyond ordinary carelessness. It means BP’s conduct showed a conscious disregard for known risks, not just bad luck or honest mistakes.
BP’s two highest-ranking supervisors aboard the Deepwater Horizon, known internally as “company men,” were the on-site decision-makers the night of the blowout on April 20, 2010. In its 2012 guilty plea, BP admitted these supervisors negligently caused the deaths of 11 workers and the resulting oil spill. The company also admitted that a senior executive obstructed a congressional inquiry into how much oil was actually flowing into the Gulf while the spill was still ongoing.
The financial consequences reflected BP’s outsized share of blame. BP pleaded guilty to 14 felony counts and paid a record $4 billion criminal penalty. Its civil settlement with the federal government and five Gulf states totaled $20.8 billion, the largest environmental damage settlement in U.S. history. When BP tallied up everything, including business loss claims, cleanup costs, and legal fees, the company estimated the disaster cost it $61.6 billion.
Halliburton: The Failed Cement Job
Halliburton was hired to cement the bottom of the Macondo well, a critical step meant to seal the space between the well casing and the surrounding rock and prevent oil and gas from surging upward. The cement failed. Investigators found the foam cement slurry Halliburton pumped into the well was unstable, and the company had test results showing as much before the job was done.
Of four lab tests Halliburton ran on various slurry designs for the final cement job, only one indicated the mixture would hold. BP may not have even received that single positive result until after the explosion. Both Halliburton and BP had data from March 2010 showing a very similar slurry design would be unstable, yet neither company acted on it. Two additional tests conducted by Halliburton in April again showed instability, and one of those results was reported internally at Halliburton by April 17, three days before the blowout. Despite all of this, Halliburton publicly claimed after the disaster that it had tested the cement beforehand and the results looked fine.
Halliburton’s assigned 3 percent of fault reflected the court’s view that while its cement work contributed to the blowout, the larger failures in well design, monitoring, and emergency response belonged to BP and Transocean.
Transocean: The Rig Owner and Crew
Transocean owned the Deepwater Horizon rig and employed most of the crew operating it. The company bore 30 percent of the fault, primarily for two reasons: its crew misread critical safety tests, and its blowout preventer, the massive device on the seafloor designed as a last line of defense, failed to work.
On the night of the disaster, the crew conducted a “negative pressure test” meant to confirm the well was sealed. The drill pipe showed 1,500 psi of pressure when it should have read zero, a strong indicator the test had failed. The crew incorrectly interpreted a lack of pressure on a different line as a passing result and essentially ignored the contradictory reading. The rig was also equipped with pressure sensors on the blowout preventer that could have confirmed the problem, but there is no evidence anyone checked them.
The blowout preventer itself had multiple failures. Its upper annular preventer, a rubber seal designed to choke off flow, likely failed because the sealing rubber had eroded. More critically, the blind shear ram, a pair of hydraulic blades meant to cut through the drill pipe and seal the well as a last resort, was not rated to shear the size of drill pipe being used on the Macondo well. A higher-capacity version existed and was rated for the larger pipe, but it was not installed. These maintenance and equipment choices meant that even after the blowout began, the safety system that was supposed to prevent a catastrophe could not do its job.
Transocean pleaded guilty to criminal charges in January 2013 and paid $300 million in criminal fines directed toward Gulf restoration and oil spill prevention training.
The Regulator That Wasn’t Regulating
The Minerals Management Service (MMS), the federal agency responsible for overseeing offshore drilling, was widely criticized for systemic failures that allowed the conditions leading to the disaster. MMS relied heavily on the oil industry to self-report its operations and production data. The agency had few formal regulations governing its own inspection program, and inspectors in the Gulf of Mexico region operated largely independently with little direction on what to inspect or how to do it.
This created what investigators described as a persistent possibility of undue industry influence over the agency meant to police it. After the disaster, the Obama administration dissolved MMS and split its functions into separate agencies to create a wall between revenue collection from oil leases and safety enforcement.
Where the Money Went
The combined $20.8 billion federal settlement resolved all civil and criminal claims against BP, Transocean, Halliburton, and a fourth company, Anadarko, which held a minority stake in the well. Of that total, $8.8 billion was dedicated specifically to restoring natural resources damaged by the spill: $1 billion committed during early restoration efforts, $7.1 billion to be distributed over 15-plus years beginning in 2017, and up to $700 million reserved for environmental injuries not yet known at the time of the agreement.
BP also funded $500 million in Gulf-related research in 2010. Half of its $4 billion criminal penalty was directed specifically toward benefiting the Gulf region. These funds have supported wetland restoration, fisheries recovery, water quality improvement, and wildlife habitat projects across all five Gulf states.
Individual Accountability
While the corporate penalties were historic, individual accountability was limited. BP’s two well site leaders aboard the rig faced criminal charges, and a senior BP executive was charged with obstruction for misleading Congress about the flow rate during the spill. However, obtaining convictions of individuals proved far more difficult than penalizing the companies. The cases highlighted a recurring pattern in industrial disasters: corporations pay enormous sums, but the people who made the decisions rarely face equivalent personal consequences. The 11 workers who died on the rig, and the families they left behind, remained at the center of public attention throughout the years of litigation.