Ciaran McNamara, partner at Pinsent Masons, writes about how two decades of delay risk undermining confidence in Northern Ireland's wider infrastructure pipeline, despite the Court of Appeal reinstating approvals for the A5.
Almost two decades after it was first announced, construction of the long-awaited £1.7bn A5 dual carriageway has yet to commence, despite extensive planning and public expenditure. The last update provided to Stormont's Infrastructure Committee, in early 2026, put that into perspective: almost £200 million had already been spent on the project, almost double the figure reported two years earlier, without construction work having even started.
First announced in 2007, the proposed 58-mile dual carriageway would link Derry to Aughnacloy, running through Strabane and Omagh. The scheme is intended to enhance connectivity across the north-west, support regional economic development and address longstanding road safety concerns along the route.
The safety imperative is stark. More than 50 people have lost their lives on the existing A5 since 2006. For the families of those who have lost loved ones, the project represents a commitment that remains unfulfilled.
Infrastructure Minister Liz Kimmins has argued that the potential loss of life cannot be measured in purely financial terms. The Department for Infrastructure has similarly maintained that the proposed dual carriageway would significantly reduce the risk of future fatalities.
Climate obligations and infrastructure delivery
The A5 and its longstanding legal battles have also become a test of how major infrastructure decisions should be made in the context of legally binding climate obligations.
The latest challenge was brought by the Alternative A5 Alliance, a group comprising residents, landowners and farmers opposed to the scheme in its proposed form. In June 2025, the High Court quashed the decision to approve the project, finding, among other matters, that the Department for Infrastructure had failed to comply with its obligations under the Climate Change Act (Northern Ireland) 2022.
The decision did not dismiss the road safety or wider public-interest objectives of the scheme. Rather, it focused on whether the government had adequately demonstrated that its decision complied with its statutory climate duties.
The High Court's decision was appealed and, on 6 October 2026, the Court of Appeal allowed the appeal and overturned the High Court ruling. The Court of Appeal concluded that the Department for Infrastructure had acted lawfully when approving the scheme and that there is no inherent incompatibility between infrastructure development and meeting Northern Ireland's statutory climate obligations.
In doing so, the Court of Appeal held that compliance with section 52 of the Climate Change Act requires the relevant department to reach a rational conclusion, following adequate inquiry, that the exercise of its function is, so far as possible, consistent with achieving the statutory emissions targets.
That is a fundamentally important distinction. A department does not have to establish that an individual project can, in isolation, demonstrate its own complete route to net zero. Nor must essential infrastructure remain at a standstill until every carbon budget, climate action plan and sectoral pathway has been finalised. The department must, however, engage meaningfully with the information available, make adequate inquiries and reach a rational and properly informed conclusion. Climate legislation does not prevent major infrastructure schemes from proceeding, but it does require decision-makers to demonstrate that they have properly considered their statutory responsibilities.
A pragmatic but demanding standard
While the Court of Appeal's decision provides reassurance for the A5 scheme, it has also brought into sharp focus a question that extends beyond the A5: how should public authorities reconcile the need for new infrastructure with legally binding climate commitments?
In its decision, the Court of Appeal adopted a pragmatic approach. Climate obligations should be addressed through a joined-up and cross-departmental approach, rather than by subjecting every individual infrastructure decision to a standard that no department could realistically meet in advance of the completion of the wider policy framework.
That does not mean that the evidential bar is low. Public authorities must ensure that their climate assessments are sufficiently detailed, transparent and legally defensible.
Furthermore, each infrastructure decision will turn on its own facts and on the evidence gathered in support of it. As the policy framework matures and the statutory targets draw closer, the degree of scrutiny applied to departmental decision-making is likely to increase.
The practical takeaway for anyone promoting or advising on an infrastructure scheme is therefore clear: build the evidential record early and build it well.
Project promoters and public authorities should document how emissions have been assessed, what cross-departmental engagement has taken place, what alternatives and mitigation measures have been considered, and how the project fits within the broader policy pathway. That work should be undertaken even where relevant climate action plans, carbon budgets or sectoral pathways have yet to be finalised.
For contractors and other delivery partners, the implications are equally direct. Legal and environmental challenges can stall major schemes, erode programme certainty and escalate costs long before work begins. Those tendering for or delivering major public infrastructure should therefore understand the environmental and legal status of a project before committing significant resources or mobilising against it.
Lessons for Northern Ireland's infrastructure pipeline
The implications extend well beyond the A5.
Projects of regional importance cannot be allowed to become indefinitely trapped between planning, litigation and funding uncertainty. Northern Ireland needs a more integrated approach that brings together infrastructure planning, environmental expertise, legal advice, public finance and delivery strategy from the outset.
The judgment is relevant to any major project requiring the exercise of public-sector powers, including transport, energy, water, waste, housing and social infrastructure. Although the factual context will differ from project to project, the Court's analysis of section 52 is likely to be relied upon wherever the climate compatibility of government decision-making is challenged.
Infrastructure providers and their delivery partners also have a role to play. Contractors, designers and consultants increasingly hold much of the information that departments require to assess embodied carbon, construction emissions, operational impact and potential mitigation. Effective engagement between the public and private sectors will therefore be critical to producing decisions that are both environmentally robust and capable of withstanding legal scrutiny.
The A5 is not a straightforward choice between building a road and protecting the environment. It is a test of whether government, and the industry that supports it, can deliver essential infrastructure while meeting legal obligations and maintaining public trust.
Northern Ireland needs infrastructure that is both deliverable and sustainable. The projects most likely to proceed successfully will be those for which environmental compliance, legal resilience, funding and delivery planning are aligned from the outset.
Wider implications across the UK and Ireland
Although Northern Ireland's statutory climate framework has its own particular features, the A5 judgment may nevertheless attract attention beyond Northern Ireland. In particular, it provides important guidance on the extent to which public bodies must take statutory climate objectives into account when exercising discretionary powers.
The position highlighted by the A5 decision is not unique to Northern Ireland. The recent ‘Coolglass' decision in the Republic of Ireland similarly emphasises that climate obligations cannot be treated as an afterthought. Public bodies must engage with the relevant statutory climate framework when exercising their powers and making decisions affecting major infrastructure.
While the precise legislation and relevant legal tests may differ between jurisdictions, the direction of travel on both sides of the border is clear: climate compliance must be embedded in infrastructure decision-making from the beginning. Where it is not, even strategically important projects may face material legal and delivery risks.
Neither the A5 decision nor the Coolglass decision requires every individual project to achieve carbon neutrality in isolation. The common principle is that, where a statutory climate framework exists, decision-makers must engage actively and demonstrably with it.
Looking ahead
The Court of Appeal's decision is undoubtedly significant. It provides much-needed clarity on what climate compliance means in practice for the delivery of major infrastructure in Northern Ireland.
It also confirms that climate law should not operate as an automatic veto on properly planned infrastructure. Robust, evidence-based decision-making can be upheld by the courts, and departments do not need to wait for every aspect of the climate policy framework to be finalised before lawfully approving essential projects.
The judgment is not, however, a licence for climate considerations to be addressed superficially. The quality of the inquiry, the evidence assembled and the reasoning recorded will remain central to the lawfulness of future decisions.
The finalisation of Northern Ireland's Climate Action Plan and carbon budgets will further shape the evidential landscape. As those frameworks develop, public bodies, government departments and project promoters should expect greater scrutiny of how emissions and climate targets have been assessed and documented.
The wider lesson is that legal compliance and infrastructure delivery cannot be treated as separate workstreams. The window to establish robust climate governance and evidence-gathering processes is now.
For the A5, the Court of Appeal has removed a major obstacle. The challenge for government and the wider industry is to translate that legal clarity into a credible, funded and deliverable construction programme. After almost two decades of delay, Northern Ireland cannot afford to lose another decade.
