The Weston Front campaign group have taken their fight to the High Court
Campaigners against government plans to build an eco-town in Oxfordshire have taken their challenge to the High Court.
Proposals for the Weston Otmoor site, near Bicester, include plans for 15,000 new homes.
It is among 10 sites shortlisted for "environmentally-friendly" towns.
The Weston Front Protest group has joined forces with campaigners against a planned site in Warwickshire to seek an order blocking the eco-town process.
The two-day challenge at London's High Court is being led by the Better Accessible Responsible Development (Bard) Campaign, which is opposed to 6,000 new homes being built near Long Marston, Warwickshire.
The campaigners have asked Mr Justice Walker for a declaration that it would be unlawful for the government to continue its present eco-town programme until there has been a proper and full consultation process.
This, they argue, should include consultation on whether eco-towns are the right way to meet the housing needs of England, or whether there are genuine alternatives.
A spokesman for the Department of Communities and Local Government said no decisions had yet been made concerning the eco-towns.
"We are currently consulting on both the shortlist of locations and our proposed standards," he said.
"We believe we have acted properly throughout this process and will defend this claim vigorously."