More than 40 people were injured in the Buncefield depot blast
Victims of the Buncefield oil depot explosion have begun their legal fight at the High Court for compensation.
The blast at the Hemel Hempstead site in 2005 was the largest in Europe since the end of World War II.
Total UK and Hertfordshire Oil Storage Ltd admitted negligence by a duty supervisor but said this did not amount to civil or criminal liability.
Homeowners, businesses and insurers hope the three-month hearing will decide who was liable for the blast.
The hearing will focus on what damage could have been reasonably foreseen and whether the operating company, Hertfordshire Oil Storage Ltd (HOSL), or Total UK Limited, which is a shareholder of HOSL along with Chevron Limited, was liable.
The explosion was the result of an overspillage of 300 tonnes of petrol from the top of one of the storage tanks, which formed a vapour cloud and ignited, causing "catastrophic and widespread" damage and injuring 43 people.
Jonathan Gaisman QC, representing individual and business claimants outside the site's perimeter fence, said the defendants disputed any liability to claimants beyond a circle of 451m radius from the depot's pump pad area on the basis that the incident was not foreseeable.
He said it was admitted that a violent explosion was foreseeable, but not one as violent in its effects as the one that occurred.
"The claimants say that the defendants' stance on foreseeability, quite apart from being bereft of merit, is bad both in law and on the facts," he said.
"It is hard to find any precedent for such a defence being argued, let alone in a case of this gravity," said Mr Gaisman.
The hearing continues.