In the penalty phase of a trial over the worst offshore disaster in our nation’s history, the oil giant cited low oil prices and its extensive cleanup efforts in seeking a lesser fine. BP is facing as much as $13.7 billion in potential fines under the Clean Water Act for the 2010 Gulf of Mexico oil spill.

The defendant in the case is BPXP, the subsidiary of BP Plc that focuses on exploration and production. Mike Brock, BP lawyer, said oil prices had plummeted 60 percent since June, cutting BPXP’s value from $16 billion a few months ago to $5.1 billion today.

“BPXP cannot afford a penalty in the range that they are asking for, and so that’s why they are saying look to the parent,” Brock said.

Urging a fine of $11.7 to $13.7 billion, attorney for the United States Steve O’Rourke said BP and BPXP are essentially the same company.

“BP’s litigation position in this phase suggests that it still doesn’t understand the gravity of what’s happened here, they continue to focus on their own hardships rather than the hardships of the environment and the people,” O’Rourke said.

According to the Clean Water Act, a company’s ability to pay, the steps it took to clean up the spill, and its history of violations must be taken into consideration when assessing fines.