A decision to block two brothers' plan to build a multi-million pound renewable energy wind farm in the Sperrin Mountains was legally flawed, a High Court judge has ruled.
Mr Justice Treacy quashed the determination after identifying mistakes in the assessment of socio-economic benefits from the seven-turbine scheme near Draperstown, Co Derry.
Brian and Michael Quinn were denied permission to develop on their land at Mullaghturk Mountain following an application first submitted in 2004.
The Department of the Environment decided the proposed site would have a seriously detrimental impact on the Sperrins Area of Oustanding Natural Beauty.
That refusal was upheld by the Planning Appeals Commission in July 2011.
A commissioner held that the renewable energy targets and economic benefits were not enough to outweigh the environmental damage to the area.
The Quinn brothers sought to judicially review the outcome, centring their challenge on alleged procedural impropriety or unfairness in consideration of Planning Policy Statement 18 dealing with renewable energy.
In a newly published judgment, Mr Justice Treacy stated: "I am persuaded that the commissioner's assessment of the socio-economic benefits is legally flawed."
He said it was unjustified to characterise the benefits as "sketchy at best" and rejected a conclusion that they favoured the Quinns as landowners. Seven out of nine listed benefits from the proposed scheme are directed more towards the community in general, he pointed out. The judge disagreed with an assessment of some "slight" benefits to the economy during the construction phase.
An environmental statement submitted by the brothers referred to £3.5m being spent erecting the timbers, excluding the cost of the turbines themselves.
Mr Justice Treacy noted this figure was absent from the commissioner's decision, adding that such an investment at 2004 prices cannot be regarded as slight.
Five per cent of the energy costs would go in rates to the local council from the planned scheme, equating to an estimated payment of up to £350,000, he noted.
"Such a figure would be a not insignificant contribution to the local economy and it is not apparent that this was fully grasped," the judge said.
"Accordingly, the assessment was materially flawed because it proceeded on material mistakes of fact and evidentially unjustified assumptions," the judge stated.