## Facts

- An offshore well blowout at the Macondo prospect led to an explosion aboard the Deepwater Horizon drilling rig on April 20, 2010, followed by a massive oil discharge into the Gulf of Mexico.
- Thousands of private and governmental claims were consolidated in federal multidistrict litigation in the Eastern District of Louisiana.
- Phase One was a bench trial focused on liability for the blowout, explosion, and initial oil discharge, rather than damages or statutory penalties.
- BP Exploration & Production Inc. served as the well operator and decision-maker for key well design and temporary abandonment choices.
- Transocean entities owned and operated the Deepwater Horizon rig and were responsible for rig operations and certain safety-related functions.
- Halliburton served as the cement contractor for the Macondo well, responsible for cement design, testing, and placement intended to seal the well.
- The court reconstructed the sequence of operational decisions, testing results, and responses leading to hydrocarbon influx, loss of well control, and the ensuing explosion and spill.

## Issues

1. What acts or omissions caused the Macondo well blowout, explosion, and initial oil discharge.
2. Whether BP, Transocean, and Halliburton breached applicable duties of care and industry/regulatory standards in offshore drilling and well-control operations.
3. How comparative fault should be allocated among the principal entities involved in well design, cementing, and rig operations.
4. What governing law applied to liability arising from a deepwater drilling casualty on the Outer Continental Shelf, including the interaction of maritime law, OCSLA, and OPA.

## Decision

- The court found that the disaster resulted from multiple, interacting operational failures rather than an unavoidable accident.
- BP was found primarily responsible due to its control over critical well design, temporary abandonment procedures, and decisions surrounding testing and displacement of drilling fluids.
- Transocean was found negligent in rig operations and supervision, including participation in misinterpreting well-condition information and failing to ensure well-control procedures were followed.
- Halliburton was found negligent in cement-related work, including deficiencies in cement design and testing that contributed to barrier failure.
- The court applied maritime negligence principles, as extended and informed by federal law governing offshore operations, and treated the matter as one governed by maritime law and related federal statutes.

## Legal Principles

- Under maritime negligence principles, liability may be based on failure to act with reasonable care in light of the hazards of offshore drilling and foreseeable well-control risks.
- Comparative fault applies to allocate responsibility among multiple tortfeasors whose separate negligent acts combine to cause a single casualty.
- OCSLA supplies a federal-law framework for incidents arising from operations on the Outer Continental Shelf and can operate in tandem with maritime principles for offshore drilling disputes.
- OPA establishes a statutory liability framework for oil pollution from offshore facilities, including designation of a responsible party and liability for removal costs and certain categories of damages.

## Conclusion

The court’s Phase One findings attributed the Macondo blowout and the initial oil discharge to a chain of negligent decisions and operational failures by BP, Transocean, and Halliburton, with BP bearing the largest share of responsibility, and grounded liability analysis in maritime negligence principles informed by OCSLA and OPA.


In re Oil Spill by the Oil Rig “Deepwater Horizon” in the Gulf of Mexico, on April 20, 2010, 844 F. Supp. 2d 746 (E.D. La. 2012)