A5 dispute ‘a litmus test’ for infrastructure and climate ambitions

Belfast-based experts in construction disputes Jennifer Lee and Meghan Kirk of Pinsent Masons were commenting after the Northern Ireland Executive confirmed it will appeal a June 2025 ruling by the High Court that halted the £1.7 billion A5 dual carriageway upgrade.

In its ruling, the High Court acknowledged that the works planned are designed to deliver improved road safety standards but it upheld complaints raised by a group called the Alternative A5 Alliance, finding that the Executive had failed to meet its obligations under climate legislation in force in Northern Ireland before signing off the scheme. The court therefore quashed Stormont’s approval of the A5 scheme, citing non-compliance with the Climate Change Act (Northern Ireland) 2022 (the Act).

The ruling was the first major test of the Act’s enforceability in infrastructure planning. It sets a precedent for how courts may interpret statutory obligations in the context of carbon-intensive developments. 

Northern Ireland’s infrastructure minister Liz Kimmins has now confirmed, however, that the Executive is seeking to appeal the High Court’s decision, citing the regional significance of the project and the urgent need to address road safety concerns – over 50 fatalities have occurred on the A5 since 2006. 

Lee and Kirk said that, while the detail on the formal grounds have yet to be made public, it is likely that the Executive will ask the Court of Appeal to consider issues of procedural fairness and interpretation of climate duties.

On procedural fairness, they said a legal argument likely to be advanced is whether the High Court gave adequate weight to public safety and economic benefits, especially the extensive public inquiry and Planning Appeals Commission (PAC) findings which had rejected all proposed alternatives to the dual carriageway.

The Executive could also seek to argue that the environmental assessments and mitigation strategies it prepared were sufficient to show it had met its duties under the Act.

Lee said: “The A5 appeal is more than a legal dispute – it’s a litmus test for how Northern Ireland balances infrastructure ambition with environmental accountability. Legal professionals, developers, and policymakers will be watching closely as the case proceeds to the Court of Appeal.” 

Kirk added: “This appeal could reshape how infrastructure projects are assessed under climate legislation in Northern Ireland. If successful, it could clarify the evidentiary threshold for demonstrating climate compliance, influence how departments collaborate with environmental regulators like Department of Agriculture, Environment and Rural Affairs (DAERA), and affect future judicial reviews of transport, housing, and energy schemes.”

“Conversely, if the appeal fails, it may embolden further legal challenges to large-scale developments and prompt legislative reform to reconcile infrastructure needs with climate imperatives,” she said.