The European Court of Justice has ruled against Ireland, saying a proper environmental impact assessment should have been carried out before the wind farm at Derrybrien was built.
At the time of the landslide in October 2003, the wind farm at Derrybrien was the largest in Ireland.
The landslide moved nearly half a million cubic metres of earth, polluted a river and killed 50,000 fish.
Ruling against Ireland, the European Court of Justice has today said the landslide occurred because a proper environmental impact assessment was not carried out prior to construction of the wind farm.
The Government argued it was caused by failures in construction.
The ECJ ruling will have a significant impact on how the Government allows other projects to proceed before full environmental impact assessments are carried out, which has happened on a number of occasions since the Derrybrien landslide.
