An appeal by Accenture against a claim from British Gas over the implementation of a billing system has been rejected by the Court of Appeal.
British Gas is seeking damages of £182m for what it argued was a defective SAP-based platform installed by Accenture in 2006.
British Gas filed a claim in 2008 for costs it incurred after it in-sourced IT and customer service staff to resolve problems caused by the Jupiter system.
British Gas said the project caused numerous errors, which allegedly led to customer service problems and caused hundreds of customers to leave the company.
Phil Bentley, managing director of British Gas, said, "Both the High Court and the Court of Appeal have now found in our favour during these important early stages. British Gas is now one step closer to holding Accenture to account for the disruption caused to our customers."
"The evidence is plain to see: we [had] to make repairs to the system and there are fundamental design issues that we are having to address," he said.
"The Jupiter system we delivered in 2005 met all contractual requirements; it was delivered on-time and on-budget.
Centrica [British Gas' parent company] operated the system for over two years before starting the court process and it is still using the Jupiter system today," said an Accenture spokesman.
The IT supplier added that the Court of Appeal had accepted a number of Accenture's arguments in the latest episode of the lawsuit.
"In particular, it reversed the High Court's judgment on a key issue that will make it more difficult for British Gas to attribute its problems with the system to Accenture, rather than taking responsibility for fixing them itself," the spokesman added.
The full trial has been scheduled to begin on 3 October 2011.