A US judge's watershed ruling means the final cost to UK firm BP for the 2010 Gulf oil spill may eclipse $50bn (€38bn), wiping out years of profits and highlighting the risks of drilling as the industry pushes into more dangerous areas such as deeper waters and ice-bound Arctic fields.
This week's court decision that BP acted with gross negligence in the Gulf of Mexico disaster may hamstring the company financially as the industry's search for resources becomes more expensive and dangerous.
US District Judge Carl Barbier held a trial without a jury over who was at fault for the catastrophe, which killed 11 people and spewed oil for almost three months into waters that touch the shores of five states.
"BP has long maintained that it was merely negligent," said David Uhlmann, former head of the US Justice Department's environmental crimes division. He said the judge "soundly rejected" BP's arguments that others were equally responsible, holding "that its employees took risks that led to the largest environmental disaster in US history".
The case also included Transocean and Halliburton, though the judge didn't find them as responsible for the spill as BP.
The judge at the New Orleans courthouse said BP was "reckless", while Transocean and Halliburton were negligent. He apportioned fault at 67pc for BP, 30pc for Transocean and 3pc for Halliburton.
Shares in BP, which may face fines of as much as $18bn (€14bn), tumbled before recovering lost ground.
"The court's findings will ensure that the company is held fully accountable for its recklessness," said US attorney general Eric Holder.
"This decision will serve as a strong deterrent to anyone tempted to sacrifice safety and the environment in the pursuit of profit."
The ruling marks a turning point in the legal morass surrounding the causes and impact of the disaster.
Four years of debate and legal testimony have centred on who was at fault and how much blame each company should carry.
"BP believes that the finding that it was grossly negligent with respect to the accident... is not supported by the evidence at trial," the company said in a statement.