The A5 Western Transport Corridor Appeal: What the Court of Appeal’s Decision Means for Planning and Infrastructure in Northern Ireland

Hassard and Others v Department for Infrastructure [2026] NICA 42

Few infrastructure projects in Northern Ireland have attracted the public attention, political investment and legal scrutiny of the A5 Western Transport Corridor. The existing A5 is an 85-kilometre route linking Derry/Londonderry with Aughnacloy, close to the border, and is a primary north–south corridor supported and financed by both the Northern Ireland Executive and the Irish Government. The case for its replacement with a dual carriageway rests heavily on road safety: the Court of Appeal recorded submissions that, over the past decade, a person has been injured on the A5 on average every four days, and that 57 lives have been lost in 18 years.

On 6 October 2026 the Court of Appeal (Keegan LCJ, Treacy LJ and Humphreys J) allowed the Department for Infrastructure’s appeal, set aside the High Court’s order and dismissed the challenge on all grounds. The decision to proceed with the first phase of the scheme, taken with Executive approval on 2 October 2024, therefore stands, subject to any further appeal and to the court’s pending ruling on costs.

The judgment matters well beyond the A5. It is the first appellate guidance on the meaning of the general climate duty in section 52 of the Climate Change Act (Northern Ireland) 2022, and it contains important statements about the adequacy of environmental impact assessment, the handling of new environmental information, the treatment of Planning Appeals Commission (PAC) recommendations and the proper limits of judicial review. This article summarises the decision and considers what it means for developers, landowners, public bodies and planning professionals.

Background: Third Time Before the Courts

The litigation history is, in the court’s own words, “long and torturous”. A first decision to proceed was quashed in March 2013 because an appropriate assessment ought to have been, but was not, carried out in respect of the River Foyle and River Finn. A second decision was quashed in November 2018 because the Permanent Secretary had acted ultra vires while the Executive was suspended, applying the Buick principles.

The third decision followed an updated environmental statement, public consultation and a PAC inquiry that opened in 2020 and reported in 2023. The responsible Minister decided that full Executive approval was required, and the Executive approved the scheme on 2 October 2024. A statutory challenge was then brought under Article 67BA of the Roads (Northern Ireland) Order 1993 by members of the Alternative A5 Alliance and named individuals, many of them affected landowners.

The High Court decision

In June 2025 McAlinden J quashed the decision on three grounds: (a) breach of section 52(1) of the 2022 Act, and irrationality arising from an inadequate evidential basis for concluding that the decision complied with that duty; (b) failure to comply with the EIA Directive (2011/92/EU), as transposed by Part V of the 1993 Order; and (c) failure to consider, and give adequate reasons in respect of, the interference with the applicants’ Article 8 ECHR rights. All other grounds were dismissed.

An unusual procedural twist

The Department of Agriculture, Environment and Rural Affairs (DAERA), which holds lead responsibility for the 2022 Act and the Climate Action Plan (CAP), took no part at first instance. It intervened only on appeal and filed substantial new evidence, as did Friends of the Earth. The Court of Appeal remitted the climate change issue to the judge, who in March 2026 treated the new material as effectively a new case and declined to engage with it substantively, so that his original decision stood.

The Court of Appeal was openly critical of the departments, describing their approach to the litigation as “unsatisfactory” and as having caused delay, and signalling that this may become relevant to costs.

The issues on appeal

The court identified four substantive questions: whether the judge was right to quash on EIA grounds; whether he was wrong to quash on human rights grounds; whether he was wrong to find a breach of section 52(1); and whether he dealt correctly with the climate change evidence on remittal.

Issue 1: Environmental Impact Assessment

The challenge

The EIA challenge was narrow. It did not concern the overall adequacy of the environmental statement, which the PAC had found adequate. It centred on an alleged failure to assess greenhouse gas emissions from induced cross-border traffic, meaning additional trips to or from the Republic of Ireland generated because the improved road would be easier to use. The court described this as “the height of the case” against the environmental statement.

The PAC’s Recommendation 16 had asked the Department to publish, with any decision, revised emissions estimates including an estimate of emissions from induced trips originating or terminating in the Republic of Ireland. The Department did so in an annex to its decision letter. The judge held that this was new and sufficiently important environmental information that it ought to have been put out to further consultation before a decision was taken.

The Court of Appeal’s ruling

The Court of Appeal accepted the importance of public participation, citing Berkeley and Champion, and acknowledged that recent authority such as Finch v Surrey County Council favours a purposive interpretation of climate-related EIA obligations. It nonetheless held that the judge had erred, for four main reasons:

• The environmental statement was not deficient. Traffic and demand modelling had been prepared in line with recognised technical guidance (TAG) and endorsed by the PAC.

• Even if induced cross-border demand had not featured in the statement, its likely effects were included in the overall assessment and considered before authorisation. Emissions had already been assessed as “large adverse”, and the low level of additional induced travel did not realistically change that.

• The PAC had required publication of further figures, not further consultation, and that requirement was met.

• Greenhouse gas emissions had been the subject of considerable consultation. Unlike Finch, this was not a case where an issue had been consciously left out of the assessment.

The court held that the judge had, in effect, required a new environmental statement, and that this approach was “too exacting and is over and beyond the requirement to have an adequate ES”. The Department’s uncontradicted expert evidence explaining the methodology (an uplift of 1% to 3% on passenger traffic forecasts) should have satisfied the court. The court also found “considerable merit” in the argument that the judge’s approach was inconsistent with his own rejection of the challenge to updated assessments for Tully Bog, where he had accepted that updated material removing scientific doubt did not require re-consultation.

Issue 2: Human Rights and the PAC’s Time-Limit Recommendation

The challenge

Article 8 was plainly engaged. The PAC recorded a total land take of about 1,209 hectares affecting 314 farms, the demolition of eight homes and a traveller site, and 14 years of “blight”. The PAC’s Recommendation 3 proposed that any authorisation should lapse if construction had not started by the end of the 2028/29 financial year, so that uncertainty would not extend into a third decade. The Department declined to adopt it. The judge held that, in rejecting the recommendation, the Department had failed to address the human rights concerns behind it.

The Court of Appeal’s ruling

The Court of Appeal described this reasoning as “flawed”. Article 8 and Article 1 of Protocol 1 rights had been taken into account throughout, through human rights impact assessments in 2016, 2020 and 2023, a revised assessment before authorisation, the PAC’s detailed discussion and the Departmental Statement. The only remaining question was how the Department dealt with Recommendation 3.

On that point, the court held that the reasons for departing from the recommendation (the scale of the project, public funding constraints, the risk of delay from legal challenges and the effect on contractor negotiations) were “easily discernible” and adequate. Whether a rigid time limit was realistic was a matter for the decision-maker. The court also found that the judge had misconstrued the recommendation, which applied to any part of the scheme rather than only the authorised phase, and had overlooked the fact that quashing the vesting orders would itself prolong the uncertainty the PAC was concerned about. No substantial prejudice was shown, and the human rights ground failed.

Issue 3: The Climate Change Act (Northern Ireland) 2022

This is the most significant part of the judgment. Section 52(1)(a) requires each Northern Ireland department to exercise its functions, “so far as is possible to do so”, in a manner consistent with achieving the Act’s emissions targets and carbon budgets. The Department accepted that the scheme would increase emissions by 972,520 tCO2e and estimated its contribution at 0.4621%, 0.1019% and 0.1163% of the first three carbon budgets. When the decision was taken, however, neither the CAP, the sectoral plans nor the carbon budgets had been finalised.

What section 52 requires

The court drew on the Irish Supreme Court’s decision in Coolglass Windfarm v An Coimisiún Pleanála [2026] IESC 5 and accepted that a duty to act “in a manner consistent with” a goal does not prescribe any particular means of achieving it. It is for departments to choose how to further the objective and, provided the decision falls within the range of consistent outcomes or consistency is not possible, the courts will not interfere.

However, the court held that section 52 goes beyond a mere “climate sense check”. It is more exacting than the Irish provision because it is tied to specific statutory targets for 2030, 2040 and 2050 and to carbon budgets, and because it can be avoided only where compliance is not possible, not merely where it is impracticable.

The key holdings are as follows:

• The 2022 Act is not a prohibition on authorising a new road where the project has been assessed, so far as possible, as consistent with emissions reduction obligations.

• It does not require every project’s greenhouse gas contribution to be set out on a precise, quantified pathway before authorisation, nor that project-level emissions be accounted for in advance in a CAP.

• A CAP is not a prerequisite for project approval. There is a single carbon budget for each period, not separate sectoral budgets.

• Compliance requires the department to reach a rational conclusion, based on adequate inquiry (the Tameside duty), that the decision is so far as possible consistent with achieving the targets. In this field that will usually require expert scientific analysis.

The court agreed with the departments that the judge’s project-level approach was “wrong and unworkable” and would “stymie all major development in Northern Ireland”. All parties accepted that the judge’s statement of what section 52 requires, in paragraph [106] of his second judgment, was wrong.

The evidential gap and the role of the court

On rationality, the court held that the Department had sufficient information about the scheme and the pathways for transport sector emissions. It was responsible only for the transport and infrastructure sectors, and it ensured that the project’s emissions were captured. On remittal, the judge should have decided whether the evidential gap he had identified had been filled. Instead, he did not engage with uncontradicted, highly technical evidence from DAERA’s officials and the lead statistician for the Northern Ireland greenhouse gas inventory, and he interpreted the draft CAP himself without inviting submissions, which the court called a “treacherous route”.

Citing Mott, the court restated that a supervisory court must not substitute its own view for that of a decision-maker making educated predictions about the future. The Department’s assessment was “realistic and honest… in challenging terrain” and should not be read hypercritically. The irrationality finding could not stand.

A Note on Habitats Regulations Assessment

Habitats Regulations Assessment was not a live ground of appeal, but it runs through the A5’s history. The 2013 quashing arose from the absence of an appropriate assessment for the River Foyle and River Finn. In the present proceedings, the High Court rejected the challenge to the reports to inform appropriate assessment for Tully Bog, accepting that updated assessments which removed scientific doubt did not require further consultation. The Court of Appeal relied on that finding when reversing the EIA ruling.

Two lessons follow. First, a failure in HRA remains one of the most reliable routes to quashing a major scheme, as the 2013 decision shows. Second, the courts are applying a consistent principle across EIA and HRA: updated technical work that refines or confirms an assessment already consulted on does not automatically require a fresh round of consultation, whereas genuinely new material that changes the assessment may do so. Authorities should apply that distinction consistently.

Practical Takeaways

For EIA

• Adequacy, not perfection, is the test. The courts will not treat an environmental statement as a “counsel of perfection”, and information produced through the inquiry process may properly form part of the environmental information.

• Distinguish refinement from omission. Updating figures on an issue already consulted on, using a recognised methodology, is unlikely to require re-consultation. Deliberately excluding an issue, as in Finch, is a different matter.

• Document methodology. Clear and uncontradicted expert evidence explaining modelling choices by reference to recognised guidance was decisive here.

• Watch the timing. The A5 statement pre-dated May 2017, so the stricter 2017 requirements did not apply. New schemes should assume the full post-2017 regime, including the assessment of climate effects.

For public authorities and the climate duty

• Section 52 is a real and exacting duty. It is not satisfied by general assurances. Departments must gather and consider quantified, expert-backed emissions evidence and explain how the decision fits Northern Ireland’s overall pathway.

• Record that reasoning at the time of the decision. The Departmental Statement’s express treatment of the targets, carbon budget percentages and transport sector modelling was central to the outcome.

• Do not rely on putting it right in court. The court accepted the later evidence because it explained, rather than invented, the existing position. That was a narrow escape, and it has costs consequences.

• Involve the right departments early. The departments’ failure to put the climate case properly at first instance caused delay and drew criticism from the court.

• Gaps in the framework increase risk. The court noted that the absence of a finalised CAP, sectoral plans and carbon budgets “raised the risk of challenges”.

For human rights and PAC recommendations

• PAC recommendations are not binding, but departing from them requires full and clear reasons that deal with the main issues in dispute (Allen; South Bucks v Porter).

• Keep human rights impact assessments under review throughout a long-running scheme, and refresh them before the final decision.

• Landowners should note that Article 8 and A1P1 arguments based on prolonged blight will succeed only where the decision-maker has failed to engage with them, not merely because the balance went against them.

Looking Ahead

The judgment brings welcome clarity to an area that had created real uncertainty for major projects in Northern Ireland. Had the High Court’s interpretation of section 52 stood, it is difficult to see how any significant emissions-generating project could have been approved before a CAP containing project-level accounting was in place. The Court of Appeal has confirmed that the 2022 Act is not a veto on development. Equally, it has confirmed that the duty is demanding, more so than its counterpart in Ireland, and that it will be enforced through the familiar public law tools of adequate inquiry and rationality.

Practitioners should bear in mind that the judgment may be appealed to the Supreme Court and that costs remain to be decided. Developers and promoters of schemes requiring EIA should build quantified climate assessments and clear methodology into their environmental statements from the outset. Public bodies should treat section 52 as a matter to be evidenced and recorded at the point of decision, not defended after the event. Objectors and landowners should be realistic: the courts will scrutinise process and reasoning carefully, but they will not reopen the planning merits or second-guess technical judgement backed by uncontradicted expert evidence.

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*This information is intended for general guidance purposes only and does not constitute legal advice, nor should it be relied upon as a substitute for professional advice specific to your circumstances.