The Long Legal Road: On April 20, 2010, the Deepwater Horizon oil rig exploded, killing 11 people and spilling hundreds of thousands of barrels of oil into the Gulf of Mexico. The three companies involved—BP, Halliburton, and TransOcean—were named as codefendants in a federal lawsuit in September 2010.

The three have long pointed fingers at each other as being culpable for the explosion. In particular, BP blamed Halliburton for using shoddy concrete to seal the well in to place. In an internal report that is no longer available on the Internet, BP took full credit for only one of eight factors it determined caused the blowout. Both TransOcean and Halliburton responded indignantly to BP’s claims of their wrongdoing.

The companies have been embroiled in legal battles on varied fronts since the spill, with BP pleading guilty to criminal charges for manslaughter and 14 other federal counts in 2013. Halliburton paid the maximum penalty for one count of destroying evidence in July 2013, and all three companies have settled multiple civil suits with government and private plaintiffs.

The legal implications are so vast, that the U.S. District Court for the Eastern District of Louisiana created a website to help those interested follow the more than 200 cases related to the spill.

A Major Juncture: A federal judge on Thursday placed the blame solidly on BP, ruling that the company’s conduct was reckless, while Transocean and Halliburton were found to be negligent, according to the New York Times.

In a 153-page ruling, Judge Carl Barbier listed nine acts by BP that amounted to “extreme deviation from the standard of care and a conscious disregard of known risks.” He also found that BP actions contributed to Transocean and Halliburton’s ability to act responsibly. Barbier assigned 67 percent of the blame to BP, 30 percent to Transocean, and 3 percent to Halliburton.

The ruling could lead to BP being fined a possible $18 billion under the Environmental Protection Agency Clean Water Act. The company has already paid an estimated $28 billion in damages and cleanup costs and $4 billion in federal criminal penalties, the New York Times reported Friday.

Down the Path: Unsurprisingly, BP disagreed with the ruling, saying that the evidence does not prove gross negligence and it will appeal the case.

“BP believes that the finding that it was grossly negligent with respect to the accident and that its activities at the Macondo well amounted to willful misconduct is not supported by the evidence at trial,” Bloomberg News quotes a company statement as saying. “The law is clear that proving gross negligence is a very high bar that was not met in this case.”

Two days before the ruling, Halliburton settled with the government for $1.1 billion, a move that experts said was calculated to limit liability, according to a September 2 New York Times article. Transocean reached a $1.4 billion settlement, but still faces additional charges in Barbier’s court, according to the article.

There are still two parts left of the case for the court to rule on—one determining the size of the spill and another to determine Clean Water Act and other fines, according to the Washington Post.