Climate-Consistent Infrastructure Approval Requires Adequate Inquiry, Not Project-Specific Allocation in a Climate Action Plan

1. Introduction

This appeal concerned the relationship between major infrastructure development, binding climate legislation, environmental assessment and the rights of affected landowners. The Department for Infrastructure (“DfI”) challenged High Court judgments quashing its October 2024 decision to proceed with the first phase of the A5 Western Transport Corridor dual carriageway scheme and associated orders.

The applicants included members of the Alternative A5 Alliance and individuals opposing the scheme. The Department of Agriculture, Environment and Rural Affairs (“DAERA”), Friends of the Earth and representatives of the Enough is Enough campaign group participated as notice parties. Their involvement reflected the competing interests: environmental protection, affected homes and farms, regional connectivity, and the urgent need to improve road safety.

The existing A5 connects Derry/Londonderry with Aughnacloy near the Irish border. The court recognised the serious history of fatal and injurious collisions on the route. It nevertheless approached the appeal as a question of legal compliance, not as an opportunity to substitute the perceived public benefits of the road for statutory requirements.

The central holding is that section 52 of the Climate Change Act (Northern Ireland) 2022 imposes a mandatory, evidence-based obligation of consistency with statutory emissions targets. It does not require an individual infrastructure project to be separately allocated emissions within a finalised Climate Action Plan (“CAP”) before approval. The department must instead undertake adequate inquiry and rationally conclude that exercising its functions is, so far as possible, consistent with achieving the statutory targets.

2. Background, Procedural History and Outcome

A long-running approval process

The scheme had already encountered two successful legal challenges. In 2013, an earlier approval was quashed because an appropriate assessment concerning the River Foyle and River Finn had not been undertaken. In 2018, a further approval was quashed because the departmental Permanent Secretary lacked authority to make the decision during the suspension of the Executive.

The third approval followed an updated environmental statement, consultation and a Planning Appeals Commission (“PAC”) inquiry. The inquiry began in 2020 and ultimately produced its final report in 2023. The responsible Minister referred the decision to the Executive Committee, which approved proceeding on 2 October 2024.

The High Court decisions

The applicants brought a statutory challenge under Article 67BA of the Roads (Northern Ireland) Order 1993. In [2025] NIKB 42, the High Court quashed the approval on three grounds:

• non-compliance with section 52(1) of the 2022 Act and an inadequate evidential foundation for the climate-consistency conclusion;
• failure to comply with environmental impact assessment requirements concerning additional greenhouse gas emissions information; and
• inadequate consideration and explanation of the interference with Article 8 rights when rejecting the PAC’s proposed time limit on authorisation.

DAERA subsequently joined the appeal and supplied substantial evidence on climate modelling and statutory compliance. The Court of Appeal remitted the climate issue to the High Court. In [2026] NIKB 10, the judge maintained his original conclusion, treating the departmental material as effectively advancing a new case rather than substantively resolving the alleged evidential gap.

The appellate decision

The Court of Appeal reversed all three successful grounds of challenge. It held that:

• the environmental assessment process was adequate, and the particular updated emissions estimates did not require further consultation;
• the department had assessed the relevant human rights impacts and adequately explained its rejection of a fixed commencement deadline;
• section 52 did not impose the project-specific CAP requirements attributed to it by the High Court; and
• the specialist evidence established an adequate inquiry and rational foundation for the approval.

The court allowed the appeal, set aside the High Court’s order and dismissed the application on all grounds. Costs were reserved for further submissions.

3. The Governing Legal Framework

The environmental statement originated in 2016. Accordingly, the relevant environmental assessment provisions were those applicable before 16 May 2017, notwithstanding later updates to the statement. That transitional position was important: the more elaborate requirements introduced in 2017 did not automatically apply to this assessment.

4. Climate Duties: Mandatory Consistency Without a Project-by-Project CAP Veto

4.1 The obligation belongs to every department

The court emphasised a distinctive feature of the Northern Ireland legislation: climate obligations are not confined to a single environmental Minister or department. Section 52 binds each department when exercising its own functions.

DfI therefore could not treat climate compliance as exclusively DAERA’s responsibility. Equally, DfI was not required to assume responsibility for every sector affected by the scheme. Its assessment had to operate within a coordinated Northern Ireland-wide framework, with emissions captured across the relevant sectors.

4.2 “Consistent with” allows choices, but requires more than consideration

The court read section 52 according to its ordinary language, statutory context and purpose. A duty to act consistently with an objective is stronger than merely having regard to it. It nevertheless leaves room for different lawful means of achieving that objective.

This distinction matters for emissions-generating development. An individual project need not itself reduce emissions to be compatible with an aggregate statutory reduction pathway. Its additional emissions may be accommodated within wider reductions, provided that conclusion rests on adequate evidence rather than assumption.

The qualification “so far as is possible” also carries real force. The court distinguished impossibility from practical inconvenience. Departments cannot avoid consistency merely because it is difficult or administratively inconvenient to achieve.

4.3 The comparative Irish position

The court drew assistance from Irish Supreme Court authority concerning the obligation to perform public functions consistently with climate plans and objectives. It accepted that consistency can encompass a range of permissible decisions.

However, it expressly held that Northern Ireland’s duty is more exacting. Section 52 refers to specified emissions targets and carbon budgets, rather than only broadly expressed plans and strategies. Its “possible” qualification is also stricter than the Irish legislation’s “practicable” qualification. The Northern Ireland duty consequently goes beyond a general “climate sense check” (paragraphs 123–127).

4.4 What section 52 does not require

The court rejected the proposition that approval depended on:

• a finalised CAP being in place;
• the particular project being expressly identified and individually assessed within that CAP;
• a separate sectoral carbon budget; or
• a precise, quantified pathway accounting in advance for every project that might be approved before 2050.

There is one Northern Ireland carbon budget for each budgetary period, not a collection of separate statutory sectoral budgets. Sectoral plans and policies contribute to meeting that overall budget.

Crucially, this does not dispense with assessment of the road’s emissions. The rejected requirement was a particular form of project-specific allocation within the CAP or an equivalent exercise isolating the project’s effect on the entire net-zero pathway. The department still needed sufficient information about the scheme’s emissions and their relationship with achievable policy pathways.

4.5 The positive test: adequate inquiry and a rational conclusion

The court’s operative formulation appears at paragraph 131: the department must reach a rational conclusion, following adequate inquiry, that exercising the function is, so far as possible, consistent with achieving the statutory targets.

The duty of inquiry is especially important because climate forecasting depends on scientific expertise. For this scheme, the inquiry needed to address:

1. the relevant emissions levels;
2. available future policy options; and
3. whether emissions associated with the scheme would prevent achievement of the statutory targets.

4.6 Why the evidence was sufficient

The Departmental Statement acknowledged additional construction and operational emissions and the scheme’s large adverse climate effect. It explained that the emissions had been incorporated into transport assumptions and communicated to other relevant departments and the Executive.

The further evidence explained the Transport Emissions Model, the Emissions Projection Tool and the treatment of road-related emissions across construction, transport and land-use sectors. It also addressed the broader policy pathways for reducing emissions. The draft CAP contained 52 policies and proposals across nine sectors, with differing contributions expected from different sectors.

The court accepted the specialist explanation that separately adding the A5 project to the projections was neither an appropriate nor a workable accounting method. It found that the departmental evidence established consistency within the wider Northern Ireland framework and defeated the finding of an evidential lacuna.

4.7 The limits of judicial review

The court considered that the High Court had moved too far towards reassessing technical forecasts and prescribing the contents of the CAP. The judicial task was to examine the legality of the inquiry and conclusion, not to decide which scientific or policy pathway the court preferred.

This does not make departmental predictions immune from challenge. Rather, the judgment places the challenge within orthodox public law: inadequate investigation, irrational conclusions or misunderstanding of statutory obligations may justify intervention. On the uncontradicted specialist evidence in this case, none was established.

5. Environmental Assessment: Additional Information Does Not Automatically Restart Consultation

5.1 The distinction between the statement and the assessment process

The environmental statement is a central document, but it is not the entire environmental impact assessment (“EIA”). The assessment process also encompasses consultation responses, inquiry material and other environmental information considered before authorisation.

The department must therefore consider the complete relevant evidential picture. It does not follow that every later refinement must be incorporated into a new statement and subjected to another consultation exercise.

5.2 The disputed induced-demand emissions

The dispute concerned emissions from additional cross-border journeys generated by the improved road. These were not ordinary forecast journeys simply changing route: they were journeys induced by a more attractive transport network.

The original traffic modelling used a fixed-demand approach and covered roads on both sides of the border. The department explained that technical tests supported the use of that approach rather than a more complex variable-demand model.

The PAC subsequently recommended publication, with the decision, of revised greenhouse gas estimates, including emissions from induced trips originating or terminating in the Republic of Ireland. The department complied. Its additional calculations used established guidance and tested passenger-vehicle demand uplifts. The updated estimates remained within the previously identified “large adverse” impact category.

5.3 Why further consultation was unnecessary here

The High Court regarded the estimates as sufficiently new and important to require further consultation. The Court of Appeal disagreed because:

• the environmental statement was adequate and its modelling followed recognised guidance;
• the likely effects were considered before authorisation;
• the PAC’s recommendation required publication alongside the decision, not renewed consultation;
• greenhouse gas emissions had already received extensive public scrutiny; and
• the additional induced-demand estimate did not realistically change the identified level of adverse effect.

The court also attached weight to the uncontradicted expert explanation of the methodology and noted an inconsistency with the High Court’s acceptance of updated environmental material concerning Tully Bog.

5.4 The holding is fact-sensitive

The judgment does not abolish consultation on significant new environmental information. It expressly recognises early and effective participation as integral to EIA. Its conclusion depended on an already adequate assessment, extensive consultation on the relevant subject, the limited significance of the refinement and compliance with the PAC’s specific recommendation.

Nor did the unchanged “large adverse” label operate as a universal safe harbour. That classification was one part of the court’s overall assessment, alongside the methodology, scale of the additional effects and procedural history.

6. Human Rights and the Rejected Authorisation Deadline

6.1 Interference and prolonged uncertainty

The scheme affected homes, farms, community land and access arrangements. The PAC also identified psychological harm caused by approximately 14 years of uncertainty over compulsory acquisition. Article 8 and Article 1 of the First Protocol were therefore materially engaged.

The PAC recommended that an authorisation should lapse if physical construction of the relevant authorised phase or section had not begun by the end of the 2028–29 financial year. Its concern was that uncertainty should not extend into a third decade.

6.2 The department’s response

DfI declined to impose the condition. It explained that the project’s exceptional scale, public expenditure constraints, possible unforeseen delays, competing spending priorities and outstanding contractor negotiations made a rigid deadline inappropriate. It nevertheless expressed its commitment to commencing authorised works by the proposed date.

The applicants’ successful first-instance argument was principally about the adequacy of reasons and consideration: the explanation rejecting the deadline did not expressly address the human rights concern underlying the recommendation.

6.3 Reading the decision as a whole

The Court of Appeal held that this approach isolated the response to one recommendation from the wider decision-making record. DfI had undertaken repeated Human Rights Act Impact Assessments, including an updated assessment before authorisation. The PAC report and Departmental Statement also addressed interference with private and property rights.

The court found the reasons for rejecting the deadline readily discernible and within the decision-maker’s discretion. The PAC’s recommendation was not binding, and its rejection did not establish that human rights had been ignored.

The court additionally observed that quashing existing vesting orders could itself prolong the uncertainty that the recommendation sought to reduce. It found no established substantial prejudice from the alleged deficiency.

The significance is not that public infrastructure automatically prevails over individual rights. It is that an adequate overall assessment and intelligible reasons need not repeat the entire rights analysis in every passage addressing a subsidiary recommendation.

7. Precedents Cited and Their Influence

7.1 Earlier litigation and decision-making authority

Buick [2018] NIQB 43, [2018] NICA 26

The judgment identifies these decisions as the source of the principles applied when the 2018 A5 approval was quashed. Their relevance was historical: the Permanent Secretary had acted outside lawful authority during the suspension of the Executive. The present appeal concerned a later decision supported by Executive approval, so that earlier defect was not the operative issue.

7.2 Adequacy of environmental assessment

R (Blewett) v Derbyshire CC [2004] Env LR 29

This authority supplied the warning against treating an environmental statement as a “counsel of perfection”. The court’s assessment reflected that principle: an adequate statement is not invalid merely because subsequent inquiry produces additional information or refinement.

R (Friends of the Earth Ltd and another) v Secretary of State for Transport [2021] PTSR 190

Cited for its endorsement of the established approach to environmental statement adequacy, particularly paragraphs 142–150. It supported a practical assessment of whether the statutory environmental information requirements had been met, rather than an insistence on exhaustive perfection.

R (Davies) v Secretary of State [2008] EWHC 2223 (Admin)

The department relied on paragraphs 36–41 to distinguish the statement from the wider assessment process. Environmental information can emerge through an inquiry and still lawfully inform the decision. That distinction was central to the appellate conclusion that the additional estimates did not necessarily require a replacement statement or further consultation.

Re Moreland and Owenvarragh Residents Association [2022] NIQB 40; Re Newry Chamber of Commerce [2015] NIQB 65

These Northern Ireland authorities were cited as further applications of the established adequacy principles. The judgment did not develop a separate rule from either case; their role was to reinforce the existing approach invoked by the department.

7.3 Participation and the scope of climate assessment

R (on the application of Champion) v North Norfolk District Council and another [2015] UKSC 52

The court cited this decision to affirm that public consultation is an integral feature of EIA. It therefore supplied an important constraint on the flexible treatment of later information: administrative efficiency cannot replace legally required public participation.

Berkeley v Secretary of State for Environment [2001] 2 AC 603

The quoted passage emphasises that the public’s entitlement is not merely to an informed substantive decision, but to the inclusive procedure prescribed by the Directive. The Court of Appeal accepted this principle while finding that the extensive participatory process already undertaken was sufficient on these facts.

Finch v Surrey County Council [2024] UKSC 20

This decision supported a purposive approach to EIA obligations but was distinguished factually. The present assessment had addressed greenhouse gas emissions and consulted upon them extensively. It was not a case of consciously excluding an entire category of downstream combustion emissions from assessment.

R (Friends of the Earth Ltd) v Secretary of State for International Trade/Export Credits Guarantee Department (UK Export Finance) [2022] EWHC 568 (Admin)

The court discussed Thornton J’s dissenting reasoning about failure to calculate emissions and reliance on general assurances when assessing compatibility with Paris temperature goals. Its use was contextual, illustrating the possible importance of purposive and substantive scrutiny. The judgment did not treat that dissent as a binding rule determining the appeal.

7.4 Reasons and human rights justification

Secretary of State for Communities and Local Government v Allen [2016] EWCA Civ 767

This authority requires a decision-maker departing from an inspector’s view to explain the disagreement fully and clearly. It also rejects an automatically heightened reasons standard merely because the recommendation is rejected. The Court of Appeal found that DfI’s explanation satisfied the contextual standard.

South Bucks District Council and another (Respondents) v Porter (FC) [2004] UKHL 33

The applicants relied on the requirement that reasons be intelligible and adequate, addressing the principal important controversial issues. The appellate disagreement concerned application, not rejection, of that principle: the Departmental Statement adequately disclosed why a rigid deadline was considered unsuitable.

R (Nash) v Chelsea College of Art & Design [2001] EWHC Admin 538; R (on the application of the Spitalfields Historic Building Trust) v London Borough of Tower Hamlets and another [2025] UKSC 11

These authorities were cited for the proposition that more substantial interference with human rights demands greater justification. The court nevertheless found that the assessments and reasons supplied sufficient justification in context. Neither case was treated as requiring the PAC’s preferred deadline to be adopted.

7.5 Statutory interpretation and comparative climate law

R(O) v Home Secretary (SC (E)) [2023] AC 255; R (PACCAR Inc and others) v Competition Appeal Tribunal and others [2023] 1 WLR 2594; For Women Scotland v Scottish Ministers [2025] UKSC 16

These Supreme Court authorities supplied the interpretative method: ordinary statutory language must be understood in context and in light of legislative purpose. The court used that method to give section 52 substantive force without adding an unexpressed requirement for project-specific CAP allocation.

Coolglass Windfarm v An Coimisiún Pleanála [2026] IESC 5

This was the key comparative authority. Its analysis placed consistency between a mere “have regard to” duty and strict compliance, allowing a range of decisions. The Court of Appeal adopted that flexibility while expressly distinguishing the more specific targets and stricter “possible” wording of Northern Ireland’s legislation.

7.6 Inquiry, expertise and judicial supervision

R (Plantagenet Alliance) v Secretary of State for Justice [2015] 3 All ER 261

Cited for the established Tameside duty of inquiry. This provided the procedural foundation for the section 52 test: the department had to obtain sufficient relevant information before reaching its climate-consistency conclusion.

Re McAleenon's Application [2024] 3 WLR 803

The court relied on the distinction between the authority’s responsibility for relevant factual findings and the court’s supervisory role, exercised through ordinary rationality review. That distinction underpinned its criticism of the High Court’s treatment of technical evidence.

Packham v SOS Transport [2021] Env LR 10

The court identified a parallel concerning the interaction between individual infrastructure decisions and national statutory climate obligations. It reinforced the need to assess a project within the wider legislative and policy framework rather than automatically treating additional project emissions as disqualifying.

R (Friends of the Earth) v Heathrow Airport Limited [2020] UKSC 52

This authority illustrated the application of Tameside principles to a major infrastructure policy decision involving climate obligations. It supported examination of the adequacy and legality of the decision-maker’s inquiry rather than substitution of the court’s preferred climate assessment.

R (Mott) v Environment Agency [2016] 1 WLR 4338

The court cited the warning against substituting judicial views for those of a conscientious, informed decision-maker, particularly when evaluating predictions. It informed the treatment of specialist emissions forecasts, without removing the court’s jurisdiction to review their rationality.

8. Fresh Evidence, Remittal and Litigation Conduct

The court’s acceptance of the departmental evidence was accompanied by strong criticism of how it had been presented. DAERA’s absence at first instance was particularly unsatisfactory given its central responsibility for the statutory climate framework.

The Court of Appeal rejected the suggestion that the High Court judge should independently have arranged DAERA’s intervention. It considered the departmental handling responsible for avoidable delay and indicated that this could affect costs.

Nevertheless, it found that the later evidence expanded and clarified the position underlying the original decision rather than manufacturing a new justification. It was broadly consistent with the Departmental Statement and explained existing modelling and accounting arrangements.

On remittal, the judge should therefore have considered whether the evidence answered the previously identified gap. The Court of Appeal also criticised his interpretation of the draft CAP without inviting submissions.

The distinction is important: the decision accepts explanatory evidence in these circumstances, not an unrestricted power to repair an unlawful decision retrospectively. Its acceptance depended on the court’s conclusion that the evidence explained an existing, contemporaneous foundation.

9. Significance and Potential Impact

A workable but enforceable climate standard

The judgment provides an authoritative Northern Ireland framework for applying section 52 to emissions-generating development. It rejects both extremes: climate targets are not merely considerations to be noted, but neither do they automatically prohibit every project that increases emissions.

Future departments will need to demonstrate a credible connection between their decisions and achievable statutory pathways. Describing a scheme as an Executive priority does not create an exemption from section 52.

No automatic development freeze pending a CAP

The absence of a finalised CAP does not itself bar approval. However, the court recognised that missing plans and budgets increase litigation risk by making consistency harder to demonstrate. The judgment does not excuse failures to meet separate statutory planning, publication or budgeting obligations; those were not resolved as independent grounds in this appeal.

A sharper focus for future challenges

Challenges are likely to concentrate on whether emissions were properly captured, relevant expertise obtained, cross-departmental effects addressed and proposed policy pathways rationally capable of supporting the conclusion. An objection based solely on the absence of the project’s name from a CAP will not meet the test established here.

Consultation remains substantive

The EIA ruling discourages automatic repetition of consultation for every technical update. Its limits are equally important: materially new effects, a deficient original assessment or the omission of a major emissions category may present a different case.

Reason-giving is contextual, not formulaic

The human rights ruling favours reading the complete decision-making record. Authorities should still address the real concern behind an inquiry recommendation, particularly prolonged uncertainty affecting homes and livelihoods. Expressly connecting that concern to the reasons for departure remains sound administrative practice.

The principal accountability tension

Aggregate modelling can appropriately explain how development fits within economy-wide targets, but it can also make individual decisions harder for the public to scrutinise. The judgment’s insistence on adequate inquiry and a rational evidential foundation is therefore essential: flexibility in accounting must not become an absence of demonstrable accountability.

10. Complex Concepts Simplified

Carbon budget

A limit on total net emissions during a specified period. Under this framework, the statutory budget applies across Northern Ireland, rather than operating as a separate allowance for each sector or project.

Climate Action Plan

A programme of policies and proposals for meeting carbon budgets and emissions targets. It is not necessarily a list allocating an individual emissions allowance to every future development.

Tameside duty

The obligation to obtain enough relevant information to make a lawful decision. Here, that required appropriate scientific inquiry into emissions and available reduction pathways.

Rationality review

Judicial examination of whether a decision has a reasonable legal and evidential foundation, rather than reconsideration of whether the court would have made the same policy choice.

Induced demand

Additional journeys generated because an improved road makes travel easier or more attractive, rather than existing journeys simply moving to a different route.

Environmental statement and EIA

The statement supplies environmental information; EIA is the wider process of information gathering, consultation, assessment and decision-making.

Qualified rights and proportionality

Rights such as respect for the home may permit justified interference. Proportionality asks whether the interference is appropriately balanced against the legitimate public objective.

Vesting and blight

Vesting transfers land compulsorily to the acquiring authority. Blight describes the harmful uncertainty and restrictions experienced while a proposed acquisition or development remains unresolved.

11. Conclusion

The Court of Appeal restored the challenged A5 approval by rejecting an overly prescriptive approach to climate planning, an unnecessarily exacting treatment of supplementary environmental information and an unduly isolated reading of the department’s human rights reasons.

Its central contribution is a disciplined section 52 test: adequate inquiry, followed by a rational conclusion of consistency, so far as possible, with binding emissions objectives. That permits evidence-based infrastructure decisions within an aggregate climate framework without diluting the statutory targets or making a finalised, project-specific CAP entry an unexpressed precondition to approval.