Campaigners against airport expansion in the south-east today claimed a high court ruling as a "major setback" to plans to build a second runway at Stansted in Essex by 2012.
The ruling said proposals to expand airport capacity were lawful but residents and local authorities should have a say over the siting of a new runway and how much land it uses.
It backed plans to build a third runway at Heathrow in west London but said there must also be further consultations over expansion at Luton airport.
The Stop Stansted Expansion (SSE) group said the ruling was the first time that the high court had allowed a judicial review challenge to a government white paper.
Campaigners said they were uncertain what would happen next but believed alternative options for a smaller second runway at Stansted - all of which were rejected by the government three years ago - must now be put back into play.
SSE chairman Peter Sanders described the ruling as a milestone in the group's fight to block the airport's expansion.
"Fairness demands that the government should now completely withdraw its support for major expansion at Stansted and that BAA should also do the decent thing and publicly announce that it will not be proceeding with its plans for a second runway.
"We will be exploring every avenue for taking today's judgment even further, including examining the scope for appeal against certain aspects of the court decision which still leave the threat of a second runway, in some shape or form, hanging over us."
The transport secretary, Alistair Darling, said he was pleased the high court had upheld the case for airport expansion in the south-east.
"I am pleased that the high court has upheld the case for two additional runways in the south-east of England at Heathrow and Stansted and rejected calls for that part of the air transport white paper to be quashed," he said.
"The government has always accepted that the exact positioning and capacity of the runways at Stansted and Luton will be decided by the normal planning process."
A statement issued on his behalf said a balance would need to be struck between capacity and environmental issues. "[Mr Darling] anticipates that with the help both of the broad strategy of the white paper and the thorough and comprehensive guidance given in the judgment, the planning system will be able to deal with the issues both efficiently and fairly."
SSE claimed the 109-page judgment had thrown up "a host of anomalies" in government policy, including a possible breach of EU environmental legislation in the failure to carry out a preliminary environmental assessment on the rejected options for expansion.
It said none of the other four options had been assessed for commercial viability.
The group's economics adviser, Brian Ross, said architects, planners and design engineers appointed by BAA "can now put down their pencils and go off on a very, very long holiday".
Expansion at Heathrow and Stansted has been bitterly resented by many local people who fear for their quality of life.
Stansted, Luton and Heathrow are all affected. Residents' groups formed a coalition with the London boroughs of Wandsworth and Hillingdon to fight the proposals.
Local authorities in Hertfordshire and north Essex also joined in the first ever high court challenge to a white paper.
SSE campaign director Carol Barbone said: "BAA and the government now face the problem of what to do next. We very much hope they will do the decent thing and abandon all plans for a second runway at Stansted but if they stubbornly choose to continue, they must know that we too will continue to thwart these outrageous expansion plans at every turn.
"They must realise also that they have a new and urgent priority which is to address the wider problem of generalised blight which now threatens to engulf this area as a result of the government's incompetence and BAA jumping the gun."
