The council challenged Mr Gummer's decision to grant planning permission for a proposed Asda superstore in Oldbury. Mr Justice Dyson ruled that there had been a 'fatal defect' in DoE planning inspector Sarah Hesketh's decision to recommend planning permission.
Ms Hesketh had failed to properly consider the impact of the superstore on the 'vitality and viability' of the town centre of Blackheath and other retail centres outside the Sandwell area, he said.
The Oldbury site is part owned by the Black Country Development Corporation and Gazeley Properties Ltd. Ms Hesketh's recommendation prompted Mr Gummer to grant planning permission last June.
The judge rejected many of the borough's complaints, but said its criticism of Mrs Hesketh's failure to consider the impact on Blackheath was 'justified'.
Mr Gummer will now have to reconsider the planning application, raising the possibility of a second public inquiry on the proposals.
Sandwell's chair of environment and development strategy Roger Horton said: 'This is a victory for local people and common sense. It reaffirms our commitment to the regeneration of local town centres, whereas this store would only lead to degeneration.'