A Chicago court found on Wednesday that BP and its minority partner Anadarko Petroleum will be liable under federal pollution laws for civil damages and their roles in the Macondo 2010 Gulf of Mexico oil spill.

The New Orleans judge ruled that the companies are liable under the Clean Water Act and the Oil Pollution Act for the oil removal costs and damages as they collectively owned 90 percent of the Macondo well which blew up.

The acts allow for a fine of up to $1,100 per barrel of oil spilled, or $4,300 if wilful misconduct or gross negligence is found to have been a factor. An estimated 4.1 million barrels were spilled, which would mean either a $4.5bn penalty or a $17.6bn penalty if negligence is discovered.