The South Downs has never qualified as a national park in the past and should not be awarded the conservation status now, a public inquiry was told.
West Sussex County Council, for a long time the most vocal opponent of the national park plan, said designation had been consistently ruled out during the last 50 years.
Rhodri Price Lewis QC, representing the council, said the Countryside Agency risked "downgrading the currency" by creating a park in the Downs.
He said: "It is difficult to see that designation today can be justified. The criteria were not met in 1956, 1991 and 1998 and are not met now.
"Nothing has changed in the real world to come to a different conclusion from that reached just five years ago."
The council said about three per cent of the Downs was open country suitable for outdoor recreation, compared with 30 to 60 per cent in other national parks. New rights of way legislation would not increase the amount of accessible land.
The wildness of the Downs had been reduced by arable cultivation and development and the remaining tranquil areas were limited to a few "isolated islands".
Mr Price Lewis said: "The narrowness of the Downs, particularly in certain areas, increases the awareness of the busy modern world."
The council, giving evidence alongside Chichester District Council, said the Downs should remain an Area of Outstanding Natural Beauty.
If the park was approved it should be confined to the classic chalk uplands.
But the Countryside Agency, which has drawn up the park plan, said the proposal would fulfil the vision of early conservationists and preserve the Downs.
It said they were worthy of designation because of their natural beauty and the opportunities they provided for outdoor recreation.
The inquiry is due to run until September. The Environment Secretary is not expected to make a decision until 2005.
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