In April, the CJEU ruled on the People Over Wind and Sweetman case, concerning a proposed electricity cable serving a wind farm in the Republic of Ireland.
The European Union Habitats Directive includes measures to protect sites such as special areas of conservation and SPAs from the effects of development.
Under the directive, before undertaking or consenting plans or projects likely to have a major impact on such sites, a public body as the "competent authority" must carry out an "appropriate assessment".
The competent authority can normally only let the plan or project proceed if this assessment concludes that development will not adversely affect the integrity of a site protected by the directive.
As an exception, however, the authority may agree to a plan or project that would have an adverse impact if there are no alternative solutions, or the plan or project must be carried out for imperative reasons of overriding public importance and adequate mitigation or compensatory measures can be secured.
April's CJEU ruling essentially overturned a previous CJEU judgement which concluded that mitigation or compensation measures that were part of a project could be taken into account at the screening stage of a habitats regulations assessment.
But, in the new judgement, the CJEU concluded the Habitats Directive "must be interpreted as meaning that ... it is not appropriate, at the screening stage, to take account of the measures intended to avoid or reduce the harmful effects of the plan or project on that site".
In May, a planning inspector beginning his examination of the recently-submitted Central Bedfordshire Council local plan expressed concerns that the document may not be "legally compliant" in the light of the ruling.
And last week, Waverley Borough Council said that, in the wake of the court ruling, it had temporarily suspended planning decisions for new residential developments in the 5km protected zone of the Thames Basin Heaths SPA.
Now, it has emerged that the Planning Inspectorate has written to planning inspectors to provide guidance on the issue.
The letter says that if a draft local plan’s HRA report includes information that "identifies likely significant effects on European site(s) and their designated features but concludes that they can be mitigated through avoidance or reduction measures", inspectors should ask the local planning authority to "confirm the extent to which they consider their HRA report is legally compliant in light of the judgment and ask them to re-visit the screening assessment in doing so".
It says that "if the revised screening assessment concludes that an appropriate assessment (AA) is required this should be carried out".
The letter also says that inspectors should "consider whether the AA necessitates any main modifications to the plan".
It adds that "further consultation may be required on any revised screening assessment or AA".
"The Habitats Regulations require the competent authority … to consult the appropriate statutory nature conservation body and have regard to any representations made by that body", the letter says.