Somerfield, who have three stores ringing the Broughton Park site, had asked the court to stop the development which is expected to
include a food superstore to be run by its rival, Tesco.
But Mr Justice Carnwath dismissed Summerfield's judicial review challenge to the planning permission granted by Flintshire CC in January this year to D.S Property Developments Ltd for Broughton Park which is also to include a petrol station, a pub, restaurants and fast food outlets.
Council officers had recognised that the development might be contrary to Government policy which discourages large-scale out-of-town shopping developments which might damage the 'vitality and viability' of existing retail centres.
But their concerns were outweighed by the 1991 permission 'which they regarded as valid and likely to be implemented' and the council had felt 'constrained' to grant planning consent for a modified scheme on January 14 this year, the judge said.
Mr Justice Carnwath said the original planning permission had been granted by Flintshire CC's predecessor - Alyn and Deeside DC - in October 1991 and the central dispute in the case was whether it remained valid.
Between 1993 and March 1994 the developers built a roundabout on the site at a cost of£500,000 and they insisted that amounted to a 'commencement' of the development, keeping it alive for the future.
The judge said it was not his task to decide whether or not the 1991 planning permission remained valid, but whether the council had reasonably decided that it was and could still be implemented.
He rejected Summerfield's claim that the 1991 planning permission had been in 'outline' only and had expired because of the developers' failure to gain approval from the council for landscaping works within three years.
Summerfield had also argued that the roundabout's construction itself had been in breach of the 1991 planning consent and thus could not be a valid commencement.
The judge agreed a council officer who gave permission for the roundabout to be built had failed to abide by the 'formalities' of putting his decision in writing or informing the council of it.
But the question was whether the technical breach meant the construction of the roundabout did not amount to a valid commencement and the judge ruled: 'In my view it does not.'
The county council's decision to grant planning permission on January 14 this year could not be criticised as irrational, said the judge, and D.S Property had already 'incurred considerable expense' developing Broughton Park.
'For the reasons I have given this application fails,' he concluded.
Summerfield were ordered to pay the legal costs of the four-day hearing which are likely to run into tens of thousands of pounds.