Legal action against a plan to build 13,500 homes in south Oxfordshire has been refused by a High Court judge.
South Oxfordshire District Council said Mr Justice Dove refused campaigners permission to apply for a judicial review of its local plan.
Bioabundance CIC started legal action because of environmental concerns after councillors approved the plan in December 2020.
It has now appealed against the judge's decision and requested a hearing.
Tom Short, representing Bioabundance, said it was "disappointing" his client's first application was refused.
He added that the claim was "clearly arguable and Bioabundance will now proceed to puts its case to the court in an oral hearing".
In a statement, the local authority said the decision meant the court "supported the democratic decision making processes within the council".
South Oxfordshire's Local Plan - a blueprint for development up until 2035 - has cost more than £3.6m.
It proposes building thousands of homes on green and brown belt sites, including Grenoble Road, Culham and Chalgrove Airfield.
In December, a coalition of Liberal Democrat and Green councillors approved the plan.
However, cabinet member for planning Anne-Marie Simpson said the council was "faced with no real choice".
She said there was a "very real possibility of the government removing planning powers from south Oxfordshire if the plan was not adopted".
Bioabundance director and councillor Sue Roberts said "democracy died" when the government "stopped them from scrapping the hated plan".
The council first drafted a Local Plan in 2014 and has conducted about 120 studies and seven public consolations on various versions.
The government previously said it could not comment on ongoing legal proceedings.