Missing Conservation Objectives Do Not Automatically Require Planning Permission to Be Quashed

1. Introduction

This judgment concerns the relationship between mandatory environmental assessment requirements and the remedies available when those requirements have been breached. Its central distinction is between identifying an unlawful assessment and deciding whether the resulting planning permission must be set aside.

The applicants, Save the South Leinster Way and its chairperson, challenged permission for a 21-turbine wind farm and associated works at Castlebanny, County Kilkenny. The respondents included An Coimisiún Pleanála and the State respondents. Springfield Renewables Ltd, the developer, participated as notice party.

By the final hearing, the dispute had narrowed principally to missing site-specific conservation objectives for Kingfisher in the River Nore Special Protection Area and Freshwater Pearl Mussel in the River Barrow and River Nore Special Area of Conservation. The applicants maintained that the absence of those objectives invalidated the appropriate assessment and required the permission to be quashed.

Humphreys J. accepted the assessment’s legal defect but refused certiorari. The developer’s uncontested ecological evidence established that applying the subsequently adopted objectives would not change the assessment’s conclusions. The court instead granted declarations identifying the State’s omissions and the planning authority’s consequent breach.

The judgment presents itself primarily as an application of settled remedial principles, rather than the creation of a renewable-energy exemption from environmental law.

2. Background and Procedural Setting

The development and protected sites

The developer applied for strategic infrastructure permission under section 37E of the Planning and Development Act 2000 on 28 January 2021. Permission was granted on 26 September 2022. The development traverses the southern section of the South Leinster Way, part of the European E8 walking route.

The project’s connections with nearby watercourses brought European protected sites into consideration. The planning authority conducted a stage-two appropriate assessment and concluded that the development would not adversely affect their integrity, subject to the proposed mitigation and permission conditions.

The outstanding proceedings concerned two species:

• Kingfisher: detailed objectives for the River Nore SPA were not published until 2 July 2024.
• Freshwater Pearl Mussel: the relevant species-specific objectives for the River Barrow and River Nore SAC were absent until 6 June 2025.

The second issue required care. Conservation objectives existed for the SAC from 2011, but the court distinguished objectives for the Nore freshwater pearl mussel from the missing objectives for Freshwater Pearl Mussel. The later scientific and taxonomic treatment of those populations did not provide a complete answer to the historical omission.

How the litigation narrowed

In Save the South Leinster Way & Another v. An Bord Pleanála (No. 1) [2023] IEHC 577, the High Court initially set aside leave on a timing objection. The Supreme Court reversed that conclusion in Save the South Leinster Way & Another v. An Bord Pleanála [2024] IESC 55 and remitted the proceedings.

Most substantive challenges were subsequently dismissed in Save the South Leinster Way & Another v. An Bord Pleanála (No. 2) [2025] IEHC 541. Those challenges included development-plan, environmental impact assessment and other ecological issues.

The applicants later withdrew their challenge to the correction of a turbine-dimension condition under section 146A. A conditional challenge concerning a ministerial direction also ceased to arise because no final direction had issued or was pleaded to have been deemed issued. The present judgment therefore did not reopen those matters.

The surviving issues were the consequences of the missing conservation objectives and a separate allegation that the State had failed to establish conservation measures.

3. Legal Framework

Conservation objectives and appropriate assessment

Article 6(3) of Directive 92/43/EEC, the Habitats Directive, requires appropriate assessment of plans or projects likely to have a significant effect on a protected site. The assessment must examine their implications in view of that site’s conservation objectives. Section 177V of the Planning and Development Act 2000 forms part of the domestic implementation framework.

Site-specific conservation objectives identify the ecological condition to be maintained or restored. They supply the benchmark against which a project’s effects must be assessed. For Kingfisher, the later objectives addressed matters including population, productivity, nesting features, foraging, water quality, connectivity and disturbance.

The judgment also distinguishes these objectives from conservation measures: the practical, regulatory or management arrangements intended to protect or restore a site. Objectives describe the required ecological result; measures help deliver it.

Different obligations for different purposes

State obligations concerning site protection and management are related to, but distinct from, the planning authority’s project-specific assessment duty. Article 6(1) addresses conservation measures for SACs. For SPAs, the Birds Directive, Directive 2009/147, is relevant; Article 7 of the Habitats Directive applies Article 6(2)–(4), rather than Article 6(1), to those areas.

The developer raised that distinction against the way the SPA claim had been pleaded. The court did not need to resolve every aspect of that objection: the conservation-measures claim failed on its pleaded factual basis, while the operative declarations referred to both directives.

Remedial autonomy

National courts generally apply domestic remedial procedures to EU-law claims, subject to equivalence and effectiveness. In broad terms, EU claims must not receive less favourable treatment than comparable domestic claims, and national rules must not make EU rights practically impossible or excessively difficult to enforce.

The disputed question was whether those constraints permitted the court to refuse to quash a permission despite the admitted assessment defect.

4. Summary of the Decision

The proceedings were otherwise dismissed, leaving the planning permission standing. The proposed costs disposition allowed the applicants only the costs attributable to the successful declaratory claims, with otherwise no order as to costs, subject to contrary submissions within seven days.

5. Analysis: The Principal Authorities

A. The assessment defect: Knocknamona and Massey

The decisive substantive authority was the CJEU’s judgment in Joined Cases C-27/25 (Knocknamona) and C-356/25 (Massey), delivered on 16 July 2026.

As recorded by the High Court, the CJEU held that a valid appropriate assessment could not be conducted without the prior adoption of conservation objectives specific to the SPA concerned. Those objectives were not optional: their absence deprived the assessment of a sufficiently precise and complete foundation.

The CJEU also distinguished identifying a geographical area potentially affected by a project from assessing the probability or risk of significant effects on a protected site. Although the former exercise might sometimes proceed without site-specific objectives, the latter required them.

This authority established the error in the present case. Humphreys J. did not treat generic objectives, inferred objectives or a favourable ecological prediction as substitutes for prior adoption of the required objectives.

However, the court held that the CJEU had not determined the separate remedial question whether every such error required an existing permission to be quashed. That distinction allowed the substantive assessment requirement and domestic remedial discretion to operate together.

B. The EU-law basis for harmless error: Altrip

The principal remedial authority was Gemeinde Altrip and Others v Land Rheinland-Pfalz, C-72/12, ECLI:EU:C:2013:712.

The High Court relied particularly on paragraph 53. A reviewing court may conclude that a contested decision would not have been different without the defect, using the case-file material and, where appropriate, evidence from the developer or competent authorities. Crucially, it must not place the burden of proving that causal connection on the applicant.

Three propositions followed:

1. Not every established environmental assessment error necessarily requires annulment.
2. The court may receive developer evidence when deciding whether the error affected the result.
3. Those asserting harmlessness must establish it.

The applicants argued that Altrip concerned standing and could not justify preserving a permission unsupported by a valid appropriate assessment. The court rejected that restrictive interpretation, reading the decision as part of a wider body of authority recognising that breach and remedy are separate questions.

A significant analytical boundary remains: Altrip arose under the environmental impact assessment regime. The present judgment applies its remedial reasoning to a Habitats Directive defect. That is the High Court’s conclusion about the combined authorities, not an express ruling by the CJEU in Knocknamona/Massey on this precise remedial issue.

C. Irish harmless-error decisions

The court relied on Carrownagowan Concern Group v. An Bord Pleanála [2025] IESCDET 9 and Massey v. An Bord Pleanála [2025] IESCDET 126. Both Supreme Court determinations described the proposition that not every judicial-review error requires quashing as well established.

The Massey determination was especially relevant because it concerned uncontested evidence that missing conservation objectives made no difference. The Carrownagowan determination also recognised that a reviewing court could rely on developer evidence without necessarily returning the matter to the original decision-maker.

Humphreys J. expressly acknowledged the non-precedential character of these determinations. They supported his understanding of existing law; they were not treated as equivalent to fully reasoned appellate judgments establishing a new rule.

The judgment also drew on Carrownagowan Concern Group v. An Bord Pleanála (No. 3) [2024] IEHC 549, Massey v. An Bord Pleanála (No. 2) [2025] IEHC 206 and other domestic decisions applying materiality and harmless-error reasoning.

D. Statutory non-compliance and structured discretion

Pat O'Donnell & Co. v. Dublin City Council [2026] IESC 36 supplied the principal structure for considering the consequences of statutory non-compliance. Drawing on Gillen v. Commissioner of An Garda Síochána [2012] 1 IR 574, it required two questions:

1. Did the legislature intend non-compliance to produce total invalidity?
2. If not, should the court nevertheless grant certiorari in the circumstances?

The first question is one of statutory interpretation. The second involves matters including substantial compliance, the seriousness of the breach, prejudice and countervailing public interests.

The applicants emphasised the Supreme Court’s warning that courts should not ordinarily excuse what the Oireachtas has required. Humphreys J. accepted the importance of that warning but rejected the proposition that describing the assessment requirement as mandatory or jurisdictional automatically resolved the remedial inquiry.

Monaghan Urban District Council v. Alf-a-Bet Promotions Ltd [1980] ILRM 64 provided part of the historical foundation for this approach. The judgment did not make substantial compliance the sole basis for preserving permission: its central finding was that the established defect had no material consequence.

E. A jurisdictional error does not itself determine the remedy

Coolglass Wind Farm Ltd v. An Coimisiún Pleanála [2026] IESC 5 was particularly important. The Supreme Court had separated an error affecting the planning authority’s powers from the subsequent question whether certiorari should issue.

That distinction answered the applicants’ reliance on Connelly v An Bord Pleanála [2018] IESC 31, [2021] 2 I.R. 752, which described a valid appropriate assessment as necessary to give the planning authority jurisdiction to grant permission. Humphreys J. treated that language as expressing an imperative legal obligation, not a universal rule requiring automatic quashing whenever that obligation was breached.

The same distinction answered reliance on FIE v An Bord Pleanála [2020] IESC 14. The court was not assuming the planning authority’s power to decide the planning merits. It was deciding the remedy for an established legal error.

F. Discretion must remain legally disciplined

Amariei v. Chief Appeals Officer [2026] IESC 22, Kelly v. Minister for Agriculture [2021] IESC 62 and Christian v. Dublin City Council [2012] IEHC 163 constrained the exercise of discretion.

These authorities prevent discretion from becoming an unrestricted judicial preference about a project’s merits. Refusing an otherwise justified remedy requires reasons grounded in sufficiently important legal or constitutional values.

O'Connell v. Behan [2021] IECA 186 helped organise the relevant considerations: the applicant’s conduct, the practical value of relief and its consequences for others. Here, the court concentrated on futility, proportionality, the developer’s position and the legal importance of renewable-energy delivery.

G. Evidence and the shifting burden of proof

An Taisce v. An Bord Pleanála & Ors. [2022] IESC 8 supported the ordinary rule that an applicant alleging a defect in an environmental assessment must establish it. Once the missing-objectives error was established, however, Altrip placed the burden of proving harmlessness on those defending the permission.

RAS Medical Ltd v. Royal College of Surgeons in Ireland [2019] IESC 4 supplied the approach to unresolved conflicts in affidavit evidence. Generally, where admissible evidence conflicts and no cross-examination resolves it, the party carrying the burden cannot simply assume its account prevails.

The allocation therefore mattered in both directions. An unresolved evidential conflict about harmlessness could operate against the developer. Conversely, the applicants’ failure to establish that conservation measures were absent operated against their separate measures claim.

H. Pleadings define the dispute

The court relied on authorities including Concerned Residents of Treascon and Clondoolusk v. An Bord Pleanála [2024] IESC 28 and Casey v. Minister for Housing, Planning and Local Government & Ors. [2021] IESC 42 for the requirement that applicants remain within their pleaded case.

The applicants had alleged an absence of conservation measures. They could not replace that claim through submissions with a different argument that existing measures were legally inadequate because objectives had been missing. The judgment treats that distinction as substantive, not merely stylistic: the alternative claim required proper pleading and an evidential foundation.

I. EU remedies, regularisation and public participation

The judgment invoked C-201/02 Wells for national procedural autonomy, subject to EU-law constraints. It also distinguished Commission v Ireland (Derrybrien Wind Farm), C-261/18, ECLI:EU:C:2019:955, concerning the exceptional circumstances in which after-the-event assessment may permit a consent to remain effective.

The distinction was between remedying material consequences of a breach and receiving evidence that a particular breach had no material consequences. The court placed this case in the latter category.

UK authorities, including Walton v. Scottish Ministers [2012] UKSC 44, R (Champion) v. North Norfolk District Council [2015] UKSC 52 and R. (Bradbury) v. Brecon Beacons National Park Authority [2025] EWCA Civ 489, supplied comparative support for refusing relief where the identified defect did not affect the decision.

Altrip also required attention to public participation. The court rejected the applicants’ participation argument as undeveloped on the facts, rather than recognising an unrestricted power to disregard participation defects.

J. Declarations and preliminary references

B. v. Child & Family Agency & Ors. [2025] IESC 2 identified three central considerations for declaratory relief: a good reason for seeking it, a real and substantial issue and an opposing party with a real interest in resisting it.

For preliminary references, the court relied on Srl CILFIT and Lanificio di Gavardo SpA v Ministry of Health, 283/81, and Consorzio Italian Management and Catania Multiservizi SpA v Rete Ferroviaria Italiana SpA, C-561/19. These authorities distinguish genuine, necessary questions of EU-law interpretation from the application of settled law. They also recognise the exceptions commonly described as acte clair and acte éclairé.

Humphreys J. concluded that Altrip already supplied the relevant remedial principle and that Knocknamona/Massey had not displaced it.

6. Analysis: How the Court Reached Its Result

The defect remained a defect

The later adoption of conservation objectives did not retrospectively make the original assessment lawful. The final declaration expressly recorded the planning authority’s contravention in undertaking the assessment without those objectives.

The later material served a different purpose: determining what remedy was justified when the court decided the proceedings.

The developer established the required counterfactual

The developer’s expert ecologist updated the Natura Impact Statement against the subsequently adopted objectives. Her evidence was that the conclusions remained unchanged, including when the project was considered cumulatively with other plans and projects.

The supporting ecological circumstances included:

• the distance between the wind-farm site and the River Nore SPA;
• the absence of suitable Kingfisher breeding or foraging habitat within the wind-farm site;
• the survey findings and absence of recorded flights at collision height;
• the proposed use of horizontal directional drilling for the relevant river crossing;
• the mussel survey results and evidence about downstream habitat suitability; and
• water-quality, sediment-control, spill-response and habitat-protection measures.

The applicants neither produced contrary expert evidence nor sought to cross-examine the ecologist. The court found that the developer had positively discharged its burden, not merely that the applicants had failed to prove actual damage.

The working test was whether the court could exclude a reasonable possibility that the error would have changed the actual outcome. A purely theoretical possibility was insufficient, but absolute certainty was not required.

Receiving evidence was not conducting a new appropriate assessment

The applicants argued that the court could not replace the statutory decision-maker’s assessment. The court agreed with the underlying separation of functions but rejected its proposed consequence.

On its analysis, evaluating evidence about materiality for remedial purposes was not equivalent to granting permission or performing a fresh statutory assessment. This distinction is essential: without it, the court’s reasoning would amount to judicial reconstruction of an assessment that EU law required the competent authority to perform.

Additional considerations supported refusing certiorari

The court also relied on the urgent legal and public interest in renewable-energy infrastructure, the disproportionate consequences for the developer, the time elapsed since the 2021 application and the availability of a declaration.

Its climate discussion referred to domestic emissions-reduction legislation, EU climate and renewable-energy instruments, and Verein KlimaSeniorinnen Schweiz and Others v Switzerland. These supplied legally recognised countervailing interests rather than merely a judicial preference for wind energy.

Importantly, the court did not decide that climate objectives permit environmental harm to be overlooked. It expressly left unresolved a possible question associated with Eneco Wind Belgium, C-325/25, about renewable energy’s overriding public importance where a breach has material effects. That question was unnecessary because the evidence here established harmlessness.

Why declarations were nevertheless justified

The court considered declaratory relief exceptional in a harmless-error case. An admission of error should not automatically entail a declaration and associated costs; otherwise, authorities might be discouraged from making appropriate concessions.

Nevertheless, the court found sufficient public benefit in marking these particular breaches. The missing objectives concerned significant environmental obligations, and the planning authority had denied the error until the CJEU judgment clarified the position.

The declaration therefore preserved accountability without the consequences of quashing permission. The judge’s additional criteria for declarations were expressed as normal practical considerations, not an inflexible replacement for the Supreme Court’s broader equitable approach.

The conservation-measures allegation failed independently

The State produced evidence of existing conservation measures. The applicants did not establish that those measures were absent or properly plead and prove their inadequacy.

Consequently, harmless error did not arise on that limb. There was no established measures-related error whose consequences required evaluation.

7. Costs and Litigation Conduct

The court proposed allowing the applicants the costs of the successful declarations, limited to what would have been incurred had the proceedings been confined to that successful relief. It proposed no order as to the remaining costs. Those arrangements were subject to contrary submissions within seven days and should not be described as an unconditional final costs adjudication.

The judgment also discussed section 50B(3) of the Planning and Development Act 2000, which permits adverse costs consequences notwithstanding the special environmental costs regime. Potentially relevant conduct included pursuing unpleaded or evidentially unsupported claims and unnecessarily repeating arguments already rejected by authoritative decisions.

However, the court distinguished unreasonable litigation from a reasonable submission that fails. It also credited the applicants for narrowing their case, withdrawing grounds and avoiding an entire anticipated hearing module. No adverse costs sanction was imposed in the proposed disposition.

The practical message is to preserve disputed legal points efficiently while concentrating hearing time on issues that genuinely remain open.

8. Significance and Limits

A fact-sensitive route to preserving permission

The decision provides a framework for cases involving historically missing conservation objectives. It does not establish that such omissions are generally harmless. The result depended on subsequently adopted objectives, an updated ecological analysis, the original assessment material and the absence of any evidential contradiction.

Future cases may differ where the later objectives reveal an assessment gap, require different mitigation, expose cumulative effects or raise a material participation issue.

No general obligation to prove environmental damage

The applicants established a breach without proving actual ecological harm. The judgment must therefore not be read as requiring environmental challengers to demonstrate damage before obtaining review.

Once the defect was established, the burden of proving harmlessness rested on the opposing parties. Applicants were entitled to contest that proof through its methodology, factual assumptions, expert evidence or cross-examination. A developer affidavit is not automatically conclusive merely because it asserts an unchanged conclusion.

Substantive compliance remains mandatory

The decision’s most important safeguard is its continued recognition that appropriate assessment without the required objectives is unlawful. Harmlessness addresses the remedy after breach; it does not authorise planning authorities to proceed without objectives in future applications.

The remaining doctrinal tension

The judgment reconciles a strict substantive rule with flexible remedial consequences. The principal issue for future scrutiny is how far Altrip’s reasoning extends where the missing requirement is described by the CJEU as inherent in appropriate assessment itself.

Humphreys J. considered that issue settled sufficiently to refuse a reference. Nevertheless, the limits of this approach remain important: preserving a permission because an error made no difference must not become retrospective replacement of the assessment that should have occurred.

9. Complex Concepts Simplified

Appropriate assessment

An assessment of whether a plan or project could adversely affect a European protected site, judged against that site’s conservation objectives.

Site-specific conservation objectives

The ecological targets for a particular protected site and its protected habitats or species.

Conservation measures

The management actions, protections and regulatory arrangements used to achieve those targets.

Certiorari

A court order setting aside a public authority’s decision.

Harmless error

An established legal error shown not to have made a material difference to the decision. It does not mean that the breached requirement was optional.

Counterfactual inquiry

Asking what would have happened if the legal error had not occurred.

Declaratory relief

A formal judicial statement of the legal position, which can record unlawfulness without cancelling permission.

Jurisdictional error

An error affecting the authority’s legal power to decide. In this judgment, that description did not remove the separate question of remedy.

Acte clair and acte éclairé

Respectively, an EU-law answer sufficiently clear, or already sufficiently established by CJEU authority, that a further preliminary ruling is unnecessary.

10. Conclusion

The judgment separates three questions: whether an environmental obligation was breached, whether that breach affected the outcome, and what remedy should follow.

The missing conservation objectives made the assessment unlawful. However, uncontested ecological evidence established that applying those objectives would not change the result. The court therefore preserved the permission while formally declaring the breaches.

The decision supports evidence-based, proportionate remedies—not relaxation of the obligation to conduct a lawful appropriate assessment before granting consent.