The council came unstuck over a 1997 decision to grant permission for a non-food retail development at the Victoria Business Park, Roche, beside the A30 trunk road.
The council was forced the modify the planning consent - striking out the non-food retail element - and that left it to face a massive compensation claim from developers behind the scheme - Land and Property Ltd.
Now Mr Peter Clarke, a fellow of the Royal Institute of Chartered Surveyors sitting at the Lands Tribunal in London, is being asked to decide on the amount of Land and Property's compensation pay-out.
The company is claiming almost £70,000 for expenditure which it says turned out to be 'abortive' and more than £4m for depreciation in the value of its land-holding. It is also claiming large sums in professional fees and interest, making a total of around £6m.
However, Mr Christopher Katkowski, for the council, argues the abortive expenditure claim is 'notional rather than an actual loss' and is not recoverable by Land and Property 'as a matter of principle'.
Disputing the method used by Land and Property to assess the depreciation in value of the site, the QC said the correct measure was the difference in the land's open market value with and without the non-food retail element.
The court dispute is likely to be a long and extremely costly one. It will be heard this week and for two weeks in February next year and for another week in March. Mr Clarke is not expected to give his final ruling on the compensation due to La nd and Property until the middle of 2004.
Planning consent for 125,000 square feet of non-retail space on the 20-hectare business park was first granted to the site's then owners in 1990.
Further planning permissions for non-food retail development were granted in 1993, 1994 and May 1997.
But the environment department intervened, saying the decisions appeared to be contrary to government planning policy which discouraged large-scale out-of-town retail developments which might harm existing shopping centres.
A public local inquiry was held in May 1999 and the inspector concluded that the 1993, 1994 and 1997 planning permissions all conflicted with national policy and were 'grossly wrong'.
The inspector said the proposed development would harm the vitality and viability of neighbouring shopping centres and undermine the efforts of local town centres to attract investment.
The development, she said, would also be detrimental to the free flow of traffic and would undermine the aims of the development plan and national policy to focus development on existing town centres.
The environment secretary accepted the inspector's recommendations and the council was, in March 2000, forced to modify the 1997 planning consent, striking out the non-food retail development.
A High Court bid to escape the consequences of the secretary of state's decision - on the basis that the planning permissions had been granted unlawfully in the first place - was dismissed in September 2000.
STRAND NEWS SERVICE