Appeal judges in the Court of Session have overturned a decision that had held unlawful the grant of consents for the construction of four offshore wind farms in the North Sea.

Lord Carloway, the Lord President, Lord Menzies and Lord Brodie dismissed four separate petitions for judicial review by the Royal Society for the Protection of Birds challenging plans to develop new marine electricity generating projects in the Firth of Forth and Firth of Tay.

The litigation 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.

In the course of the consent process, which resulted in ministers granting the consents in October 2014, the plans were substantially modified, reducing the total number of turbines from 488 to 335. The RSPB complained that material information had not been shared with it but had been used in reaching the decisions.

Last year Lord Stewart in the Outer House ruled that the granting of consents had been "substantively flawed and ultra vires", and in any event flawed by a proceddural irregularity of such seriousness that the decision had to be struck down. This was because 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. (Click here for report.)

However the Inner House held that the Lord Ordinary had gone beyond his proper functions in ruling as he did. Delivering the opinion of the court, Lord Carloway stated, dealing first with the regulations relating to environmental protection: “The regulations are intended to provide for the effective publication of environmental information and for public participation in the EIA [environmental impact assessment] process. The extent of such provision must, however, be tempered with a degree of realism. It should not create an endless process of notification of, and consultation on, every matter which is, or becomes, available to the decision-maker prior to the decision. The process is to inform the public of the application, and its perceived environmental impact, and the responses from defined statutory consultative bodies (additional information). The public then have an opportunity to comment on these matters and, no doubt, to raise any concerns about other issues which they perceive to arise. That process was fully complied with here.”

He concluded on this point: "The Lord Ordinary’s focus on the EIA Directive, rather than the EIA and Marine Works Regulations, was an error. His conclusion, based on the directive, that, if the respondents relied upon any information which had not been consulted upon, they would act ultra vires was also erroneous. For the reasons already given, the information which requires to be put in the public domain is defined by the implementing regulations. In the absence of a challenge to the regulations, their plain terms govern the vires of the respondents’ actions."

On the standard of review the court should apply, the Lord President said: “Despite paying lip service to the correct legal test for judicial review, the Lord Ordinary has strayed well beyond the limits of testing the legality of the process and has turned himself into the decision-maker following what appears to have been treated as an appeal against the respondents’ decisions on the facts. He has acted almost as if he were the reporter at such an inquiry, as a finder of fact on matters of scientific fact and methodology which, whatever the judge’s own particular skills may be, are not within the proper province of a court of review. For this reason alone, his decision on this ground cannot be sustained.”

He had also erred in holding that the ministers’ reasoning had been inadequate: “The decision letters are detailed documents covering a wide variety of issues. Again, however, the reasons for reaching the decisions are clearly set out both in a specific summary form and in the preceding more expansive format. Due process had been carried out. The ESs (environmental statements) had judged the likely impact to be acceptable. The projects would contribute to local or national economic development priorities and the respondents’ energy policies. On the basis of the AA [appropriate assessment], the respondents had determined ‘to the appropriate level of scientific certainty’ that the projects would not adversely affect site integrity in view of their conservation objections… The respondents stated that, having taken into account the relevant information from the applicants, the consultative bodies’ responses, the AA and both the mitigation measures and conditions imposed, there were no outstanding concerns requiring consent to be withheld. This is again sufficient to meet the legal test of adequacy.”

The RSPB expressed dismay at the ruling, claiming that the developments "could be amongst the most deadly wind farms for birds anywhere in the world". It did not regret bringing the action., which had been taken "as a last resort".

Developers Mainstream Power welcomed the ruling and said it planned to move ahead quickly with construction of the Neart na Gaoith scheme in the outer Forth, which would be capable of providing clean energy to a city the size of Edinburgh.

Energy Minister Paul Wheelhouse said protecting the marine environment remained of "paramount importance" in considering plans for renewable energy developments.

Click here to view the opinion of the court.