Harmless Error Doctrine in Appropriate Assessment Screening under the Habitats Directive

Introduction

This commentary examines the High Court’s decision in Massey v An Bord Pleanála & Ors [No. 2] [2025] IEHC 206, delivered by Humphreys J. on 11 April 2025. The case arises under Sections 50, 50A and 50B of the Planning and Development Act 2000, as amended, challenging the grant of planning permission for a 17-turbine wind farm on the Cork/Waterford border. Central to the dispute were:

The statutory pre-application (“SID”) process under s. 37A–37G
Screening for Appropriate Assessment (AA) under Article 6(3) of the Habitats Directive
The requirement (or not) for site-specific conservation objectives and measures under the Birds and Habitats Directives

Parties included Paddy Massey as applicant, An Bord Pleanála, the Attorney General and the Minister for Housing, Local Government and Heritage as respondents, and Curns Energy Limited as notice party.

Summary of the Judgment

The court made four key rulings:

Core Ground 1 (pre-application/SID error) warranted declaratory relief only, not quashing of the permission;
Challenges to the AA screening (Core Ground 2) and to the EIA scope (Core Ground 4) failed for lack of evidence or on their merits;
The State conceded and the court granted a declaration that, prior to 26 March 2024, no site-specific conservation objectives existed for the Blackwater Callows SPA and that no conservation measures have been put in place;
The question whether lacking conservation objectives renders Stage I AA screening jurisdictionally invalid was referred to the Court of Justice of the European Union (C-27/25) for a preliminary ruling—but quashing was refused as the error made no difference on the facts.

Analysis

Precedents Cited

Cork Harbour Alliance v An Bord Pleanála [2021] IEHC 203 – pre-application applicant identity;
Callaghan v An Bord Pleanála [2018] IESC 39 – scope of pre-application decisions;
Carrownagowan Concern Group v An Bord Pleanála (Nos. 2 & 3) [2024] IEHC 300 & 549 – harmless error doctrine in environmental judicial review;
Champion v North Norfolk DC [2015] UKSC 52 – Altrip’s “harmless procedural defect” principle in EIA;
Fitzpatrick v An Bord Pleanála [2019] IESC 23 – definition of “project” for EIA purposes;
Power v An Bord Pleanála [2024] IEHC 108 & IECA 295 – reference on site-specific objectives for Stage II AA;
Commission v Ireland (Protection des zones spéciales de conservation) C-444/21 – obligations to designate and set objectives for SACs;
Friends of Ardee Bog v An Bord Pleanála [2024] IEHC 292 & [2025] IESCDET 29, 13 – screening without objectives.

Legal Reasoning

The judgment rests on two pillars:

Harmless Error Doctrine: Relying on C-72/12 Altrip and Champion, the court held that even a jurisdictional error (e.g. absence of site-specific objectives at screening) does not mandate quashing if it is established—on the full evidence, including uncontradicted expert affidavits—that the error could not have affected the outcome. Here, expert evidence (Bird surveys, distance from SPA) excluded any reasonable possibility of significant effects on the Blackwater Callows SPA.
Scope of AA Screening: Article 6(3) links conservation objectives expressly to Stage II AA, not to Stage I screening. No textual link in the Habitats Directive compels objectives to precede screening. While a reference to the CJEU was made on this discrete point, the court concluded on the facts that screening without objectives here caused no material prejudice.

Impact

This decision clarifies that:

Planning permissions will not automatically fall if site-specific conservation objectives are lacking at the screening stage, provided no real risk to the site is shown.
Courts may refuse certiorari for “jurisdictional” or environmental errors that are harmless in practice, strengthening judicial restraint and proportionality.
The distinction between the threshold screening under Article 6(3) and the full “appropriate assessment” tied to conservation objectives is reinforced, pending the CJEU’s ruling in C-27/25.

Complex Concepts Simplified

Natura 2000 & AA Screening: The EU network of SPAs and SACs requires that any plan “likely to have a significant effect” be screened. If potential effects cannot be ruled out, a detailed Stage II AA by reference to conservation objectives follows.
Site-Specific Conservation Objectives: Detailed targets for habitat condition and species protection that guide full AA—absent in Ireland for many SPAs until recently.
Harmless Error (Altrip Doctrine): A procedural defect does not void a decision if the court, on all available evidence, can conclude the outcome would be unchanged.

Conclusion

The High Court’s judgment in Massey v An Bord Pleanála emphasizes judicial proportionality in environmental review. It affirms that not every procedural or “jurisdictional” lapse automatically voids a consent—courts may uphold authorizations when no real harm to protected sites is shown. It also draws a clear line between screening for AA (procedural threshold) and the substantive AA tied to conservation objectives. Although a reference to the CJEU will settle whether objectives are a jurisdictional prerequisite to screening, practitioners can take comfort that the absence of objectives alone is unlikely to batter every environmental consent in Ireland.