Summary of Judgment — Court of Appeal (Northern Ireland)

Factual and Procedural Background

The Appellant commenced judicial review proceedings on 21 May 2021 alleging that responsible public authorities had failed to investigate and abate a persistent nuisance odour and pollution emanating from a local landfill (referred to in this summary as "the City landfill site"). At the time the proceedings were issued the Appellant resided at an address within the district served by the local district council; she has since moved to another county but continues to spend some time at the original property for caring reasons.

The City landfill site is operated by a private operator, which appears in the proceedings as a notice party (hereafter "The Hospital"). The local district council responsible for investigating statutory nuisance complaints is referred to here as "Company A". The environmental regulator and the relevant departmental minister are referred to here as "Company B" and "The University" respectively.

At first instance, the High Court judge (referred to here as Judge Humphreys) dismissed the Appellant's judicial review claim on 25 May 2022. The Appellant appealed to the Court of Appeal, which on an earlier occasion found that alternative private remedies were available (including a private prosecution under the Clean Neighbourhoods and Environment Act (Northern Ireland) 2011 and civil actions in nuisance) and dismissed the appeal on that basis ([2023] NICA 15). The Appellant appealed to the United Kingdom Supreme Court, which remitted the matter to the Court of Appeal for a decision on the merits ([2024] UKSC 31), holding that the Appellant was entitled to choose judicial review and that the challenge should be judged by public law standards. This document summarises the subsequent judgment of the Court of Appeal (panel: Judge Keegan delivering the judgment, with Judge Treacy and Judge Horner) delivered on 16 September 2025 in which the court affirmed the High Court decision and dismissed the appeal.

Legal Issues Presented

1. Did Company A breach its statutory duty to take such steps as are reasonably practicable to investigate complaints about statutory nuisances under section 64(b) of the Clean Neighbourhoods and Environment Act (Northern Ireland) 2011?
2. Did Company B and The University breach their statutory duties and/or act unlawfully by failing to identify or adopt a guidance level for lifetime exposure to hydrogen sulphide (H2S) that would pose a risk, in the context of the Pollution Prevention and Control (Industrial Emissions) Regulations (Northern Ireland) 2013?
3. Did Company A, Company B and The University collectively (or individually) breach the Appellant's rights under Article 8 of the European Convention on Human Rights (respect for private and family life and the home)?

Arguments of the Parties

Appellant's Arguments

• The Appellant alleged that Company A effectively abdicated its statutory investigatory obligation by directing complainants to Company B and therefore failed to take all steps reasonably practicable under section 64(b).
• The Appellant contended that Company B and The University had a positive duty under the 2013 Regulations to engage with, and where appropriate adopt, standards or guidance on lifetime exposure to H2S (notably guidance referenced in England), and that the failure to adopt or to engage diligently with those standards was unlawful.
• The Appellant advanced a claim under Article 8 ECHR, asserting that the odour and associated symptoms interfered with her private and family life and home, and that the public authorities had failed to approach the problem with due diligence and proper consideration of competing interests.
• The Appellant also contended that errors of law made by Company A (for example, its stated belief that Company B had “primary responsibility”) were material to its investigatory choices and rendered Company A's conduct irrational.

Company A's (Council) Arguments

• Company A submitted that the statutory wording (“such steps as are reasonably practicable”) confers discretion as to how the duty to investigate is discharged; judicial review of the exercise of that discretion is confined to Wednesbury irrationality.
• Company A relied on its investigative steps and contemporaneous evidence (meetings, provision of odour diaries, daily odour monitoring, liaison with other agencies) to demonstrate that it had not abdicated responsibility but had acted rationally and reasonably.
• Company A argued any misstatement in an affidavit about the allocation of “primary responsibility” was immaterial because its actual conduct demonstrated an appropriate investigatory response.

Company B and The University's (Regulators) Arguments

• Company B and The University argued that the 2013 Regulations and associated regulatory framework require the application of Best Available Techniques (BAT), permit conditions and periodic review rather than the imposition of a single lifetime-exposure standard for H2S across all permits.
• They maintained that there is no legal obligation to publish, or to adopt, England-specific guidance values as permit conditions; guidance (including site‑specific health assessments carried out elsewhere) does not have the status of an enforceable emission limit for permits.
• They relied on their monitoring, inspections, the adoption of site-specific odour management plans, steps taken by the operator, and engagement with the public health agency to demonstrate that they had exercised appropriate regulatory oversight and due diligence.
• They submitted the court should be cautious before substituting its own view for the specialist judgment of environmental and public health agencies on technical matters.

The Hospital (Operator / Notice Party) Arguments

• The operator stated that the landfill site was nearing the end of its operational life and stopped accepting non‑hazardous black‑bin waste in or around November 2022.
• The operator explained it used landfill gas extraction for electricity generation, had implemented measures identified by the regulator (e.g. reduced working face, gas infrastructure, changes in cover) and employed best available techniques (BAT), and that monitoring had shown only rare and very faint odour on two out of forty or so assessments.
• The operator denied other alleged causal matters (for example, acceptance of gypsum) and asserted compliance with permit conditions where applicable.

Table of Precedents Cited

Court's Reasoning and Analysis

The Court structured its analysis around the three core issues identified in the appeal. The approach adopted throughout was to apply established public‑law standards: the rationality (Wednesbury) standard for review of discretionary investigatory choices by the local council (Company A), and the due diligence / proportionality framework (as developed in Fadeyeva and Richards) for Article 8 challenges to regulatory decision‑making by specialist agencies (Company B and The University).

1. Company A — statutory duty to investigate (section 64(b) of the 2011 Act)

The Court accepted the trial judge's conclusions that section 64(b) imposes a duty to take steps that are reasonably practicable to investigate complaints but that the statute's language inherently confers discretion as to how that duty is discharged. The Court drew on authorities (including Marshall, Jenkins and other historical authorities) to explain that “reasonably practicable” is a context‑sensitive standard where a public authority may weigh competing considerations (risk, cost and practicability) and choose among different reasonable investigatory steps.

The Court analysed the unchallenged factual evidence (notably the affidavits of the local authority's environmental manager) documenting Company A's engagement: meetings with other bodies, information‑sharing, distribution of odour diaries, and a programme of daily odour monitoring. On that evidential basis the Court concluded that Company A had not simply “left responsibility” to Company B but had carried out a rational investigation and had reached a conclusion (no statutory nuisance) that was open to it on the material before it. The alleged misstatement in an affidavit that Company B had “primary responsibility” was found to be incorrect in law but not material: the mistake did not have a material effect on the investigatory steps actually taken. Because the relevant standard of review is one of irrationality, the Appellant's challenge to Company A failed.

2. Company B and The University — statutory obligations under the 2013 Regulations

The Court began by setting out the statutory framework derived from the Environment (Northern Ireland) Order 2002 and the 2013 Regulations, including the role of permits, the requirement to consider Best Available Techniques (BAT), the obligation to include emission limit values where necessary, and the duty to review permits in regulation 17 when justified by significance of pollution, changes in BAT, or new standards.

The Appellant's principal contention was that Company B and The University had failed to engage with or to adopt a specific lifetime‑exposure standard for hydrogen sulphide (H2S) (for example, thresholds discussed in guidance used in England) and that regulators had therefore failed in their statutory duties. The Court considered authorities addressing the legal status of policy and guidance (notably A v Secretary of State for the Home Department and BF (Eritrea)), which make clear that public authorities are not generally obliged to promulgate detailed policies or to convert every guidance value into an enforceable statutory standard.

Critically, the Court examined the contemporaneous and expert evidence relied on by Company B — including evidence of monitoring, the adoption of odour management plans, specific enforcement actions and remedial works performed by the operator, and engagement with the public health agency (which provided specialist advice on health risks). The Court noted that UK‑based guidance relied on by the Appellant (for example arising from a different landfill inquiry in England) had been the subject of consideration by Company B and the public health agency, and that the public health agency in particular considered the contexts to be different and advised that a particular numeric long‑term H2S value should not be uncritically imported into the permit system here.

The Court also observed practical and scientific constraints (including the presence of background H2S in urban areas) and emphasised that enforcement by permit requires technical, specialist judgment that is not readily reducible to a universal numerical emission limit. Applying the rationality / due diligence lens established in the case law, the Court concluded that Company B and The University had engaged appropriately with the technical issues, had employed relevant assessment methods and monitoring, and had not acted irrationally or unlawfully in declining to adopt the particular lifetime‑exposure figure the Appellant urged.

3. Article 8 ECHR

The Court analysed the Article 8 claim against the threshold established in Fadeyeva and subsequent domestic authorities: the claimant must demonstrate both an actual interference with the private sphere and that the interference has attained the requisite level of severity. The trial judge had found that the Appellant met the minimum severity requirement and had acquired victim status; on appeal the respondents raised the issue of ongoing victim status given the Appellant's change of residence and the closure of the site to non‑hazardous waste, but the Court proceeded on the basis adopted by the trial judge that Article 8 could be engaged.

The Court applied the proportionality / due diligence framework (as explained in Fadeyeva and applied in Richards). It evaluated whether the public authorities had approached the problem with the appropriate level of diligence, including investigation, monitoring, inter‑agency liaison and engagement with public‑health expertise. Having reviewed the evidence (monitoring records, steps taken by the operator, regulatory inspections, advice from the public health agency, and the absence of substantiated complaints after a certain date), the Court concluded that the authorities had not exceeded the margin of appreciation accorded to them: they had taken reasonable and proportionate steps in the face of scientific and factual complexity. Consequently, even if Article 8 was engaged, the interference was justified and the Article 8 claim failed.

Throughout the analysis the Court emphasised the limits of judicial intervention in complex technical and scientific regulatory domains: the role of the court is supervisory, not to prescribe detailed technical standards or substitute its view for that of expert public bodies.

Holding and Implications

CORE RULING: The appeal is DISMISSED and the decision of the trial judge (Judge Humphreys) is affirmed.

The Court answered the three core questions as follows (in the language used by the Court):

• Company A (the local council) did not breach its statutory duty to investigate complaints under section 64(b) of the 2011 Act.
• Company B and The University did not breach their statutory duties by failing to identify or adopt a single lifetime‑exposure level for H2S that posed a risk.
• There has been no breach of the Appellant's rights under Article 8 of the ECHR on the evidence before the Court.

Practical consequences and implications drawn by the Court (as recorded in the judgment):

• The Appellant's judicial review claim is unsuccessful and the relief sought is refused; the trial judge's dismissal is affirmed.
• The judgment is framed as an application of settled public‑law principles (rationality/Wednesbury review for local‑authority investigatory choices; due diligence/proportionality analysis for Article 8 challenges in environmental regulation). The Court did not set or prescribe any new technical or numerical standards for regulators to adopt; it did not convert guidance used elsewhere into a legally enforceable ceiling for permits in Northern Ireland.
• The decision confirms the courts' reluctance to displace specialist regulatory and public‑health assessments by imposing numerical standards or timetables, and reinforces that where technical questions arise the appropriate remedy is regulatory and scientific engagement rather than judicial prescription.

Note: the Court's judgment does not purport to foreclose all future challenges to policy or to public‑health guidance; rather, it found on the facts and evidence in this case that the relevant authorities had exercised appropriate diligence and that no Convention breach occurred on that basis. The judgment therefore resolves the dispute between the parties but does not create a new, generalised statutory obligation to publish or adopt a particular lifetime‑exposure H2S limit.

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