In April, the European Court of Justice (ECJ) issued a judgment on habitats regulations assessment (HRA).
Under the European Union Habitats Directive, local planning authorities are required to carry out these assessments to make sure plans or projects affecting sites in and around EU-designated special areas of conservation (SACs) or special protection areas (SPAs) have no harmful effects on them.
HRA has two stages – a screening stage, which may be followed by a full "appropriate assessment".
Established practice, following the High Court ruling in R (Hart District Council) v Secretary of State for Communities and Local Government , has been that proposals to mitigate any negative impacts of a proposed plan or project, for instance by creating alternative wildlife-friendly areas, can be considered at the screening stage.
If the promoter can persuade the decision-maker at this point that the measures will effectively mitigate negative impacts, the requirement for the second "appropriate assessment" stage is avoided.
However, April’s ECJ ruling on a case from the Irish Republic, People Over Wind and Sweetman v Coillte Teoranta, appeared to overturn this interpretation. Instead, the judgment stated that "a full and precise analysis of the measures capable of avoiding or reducing any significant effects on the site concerned must be carried out not at the screening stage, but specifically at the stage of the appropriate assessment".
Now, the court has issued a judgement in a separate case which relates to the issues raised in the People Over Wind case.
According to the latest judgement, the case relates to planning permission for a wind farm project in a special protection area which hosts a protected species.
The court’s ruling confirms the previous decision, and, according to Trevor Ivory, UK head of planning at law firm DLA Piper, "takes it further".
"This case essentially confirms [the] approach and takes it further, distinguishing mitigation that consists of measures intended to avoid or reduce harm to the protected site and measures intended to compensate for any harm", he said.
The ruling states that the former should be subject to appropriate assessment under article 6(3) [of the Habitats Directive], i.e. the proposal can be permitted if the appropriate assessment concludes that the protected site will not be harmed, he said.
However, he added that the ruling says that "measures designed to compensate for any harm rather than prevent it cannot lead to permission under article 6(3), so that the proposal will fall to be considered under article 6(4), i.e. it will not be permitted unless there are, ‘imperative reasons of overriding public interest’".
Where such imperative reasons exist, "the member state is required to ensure that all compensatory measures necessary to ensure the integrity of the protected site are taken and must notify the European Commission of the compensatory steps that have been taken", Ivory said.
He added: "The result of these cases is that it is clear that mitigation does not avoid the need for a proposal to be subject to appropriate assessment, and where the mitigation proposed does not avoid harm to the protected site but rather seeks to compensate for it, the higher bar of imperative reasons of overriding public interest must be demonstrated before consent can be forthcoming."