Live: Battle resumes over Gulf oil spill’s size; BP faces up to $18B fine

The legal battle over the worst offshore oil spill in U.S. history has resumed, as BP tries to cut a fine that could soar to $18 billion for unleashing millions of barrels of crude into the Gulf of Mexico in 2010.

The latest round in the ongoing courtroom saga centers on just how much oil gushed from the Macondo well during the three months it took to bring it under control.

In recent court filings for the civil trial, the government said it will argue that 5 million barrels of oil were discharged by the Macondo well and about 4.2 million barrels of oil entered the Gulf. BP will argue that 3.26 million barrels of oil were discharged by the well and about 2.45 million barrels entered the Gulf.

The Clean Water Act allows fines of $1,100 to $4,300 per barrel of oil discharged into the sea, depending on whether a well operator was grossly negligent. The maximum fine would be $18.1 billion under the government’s spill estimate and $10.5 billion based on BP’s total.

The judge has leeway to go lower than the range of fines allowed under the law.

Follow the play-by-play of the legal arguments as energy reporter Collin Eaton tweets from inside the courtroom: