Proposals for four offshore wind farms in the Firth of Forth and Firth of Tay have been halted by a successful court challenge by the Royal Society for the Protection of Birds.

Lord Stewart in the Court of Session ruled in each of four judicial review petitions brought by the RSPB, that in granting consent for the projects, Scottish ministers had failed to comply with their duties under the Electricity Works Regulations, in that they had failed to consult on environmental information and acted on unconsulted-on information; they had adopted a wrong methodology as regards ornithological risk assessment, and were in breach of EU law by refusing or delaying to classify the relevant sea area as a marine special protection area.

His rulings concerned the proposed developments of Inch Cape, Seagreen Alpha, Seagreen Bravo and Neart na Gaoith, planned to provide 2.284GW of green energy but which RSPB maintained posed a severe threat to thousands of puffins, gannets and kittiwakes, and also to guillemots and razorbills, which have protected habitats in the Firth of Forth and on the Angus coast. The risks arose from collision with turbine rotors, displacement from foraging areas within projected development sites, and "barrier effects” to flight, including foraging flights to and from breeding colonies, entailing extra energy needed by the birds with consequences for body mass, adult survival, nest attendance and chick provisioning.

The judge agreed with the RSPB's submissions that material information had not been shared with it but had been used in reaching the decisions in question. This flaw "is not simply a procedural irregularity: it is substantive; and the decision is ultra vires", he ruled. "If the decision is not substantively flawed and ultra vires, the procedural irregularity is of such seriousness that the decision has to be reduced in any event. If the irregularity is not of such seriousness, I say that the decision has to be reduced because substantial prejudice cannot be ruled out, the burden being on the ministers and the interested party, Inch Cape, in this connection." It was not a case in which the court, having regard to the nature of the flaw and weighing the balance of prejudice and other relevant circumstances, could properly exercise its discretion to refuse the remedy sought by the RSPB, which was to reduce (annul) the decision.

Similar considerations applied to the separate consent under the Marine Works Environmental Impact Assessment Regulations.

As regards the risk assessment challenge, Lord Stewart said "that the task for the ministers is not an enviable one. As I understand it, there is broad support for the ministers’ policy on sustainable energy generation. The environmental determinations that have to be made are very difficult ones". However there had been a number of errors in the decision making process, and the ministers had not established that if a reassessment were carried out, the outcome would inevitably be the same.

On the EU law challenge, Lord Stewart said it was not open to him to find the ministers in breach of an obligation to classify a marine special protection area, but the area should be treated as such because it met all the criteria, and the ministers had failed to have regard to material factors and to implement their statutory duties in making their decisions.

Following the decision, the RSPB said it did not regard the outcome as a victory or loss for either side, but it wanted to see "improved environmental assessment and a more rigorous decision making process that encourages the right types of renewables in the right places".

Energy Minister Paul Wheelhouse said the Scottish Government remained "strongly committed" to offshore wind energy, and was keen to work consrtructively with RSPB and developers "to ensure the sector has a bright future".

Click here to view Lord Stewart's principal opinion.