NATIONALLY SIGNIFICANT INFRASTRUCTURE PROJECTS (NSIP) SYSTEM

1. Meaning and Purpose

The Nationally Significant Infrastructure Projects (NSIP) system is the United Kingdom’s specialised planning and consenting framework for major infrastructure projects, principally established by the Planning Act 2008. It was designed to provide a coordinated procedure for infrastructure whose scale and importance justify decision-making at national rather than ordinary local-planning level.

NSIPs can include major projects involving energy, transport, highways, railways, airports, water, wastewater and waste infrastructure, where the relevant statutory thresholds are satisfied. Section 14 of the Planning Act 2008 identifies categories capable of constituting NSIPs.

2. Development Consent Order

A central feature is the Development Consent Order (DCO). Under section 31 of the Planning Act 2008, development consent is required for development that is or forms part of an NSIP.

Instead of obtaining numerous separate permissions through conventional planning procedures, a developer generally submits a DCO application through the statutory NSIP process. A DCO can provide planning authorisation and incorporate various powers necessary to construct and operate the infrastructure.

Applications are examined through the Planning Inspectorate process, while the relevant Secretary of State ordinarily makes the ultimate decision whether development consent should be granted.

3. National Policy Statements

National Policy Statements (NPSs) are fundamental to the NSIP system. They establish national policy concerning particular categories of infrastructure and provide the policy framework against which DCO applications are assessed.

The Planning Act requires important procedural safeguards when an NPS is developed, including sustainability appraisal and public consultation. Section 10 also requires the Secretary of State, when exercising specified NPS functions, to pursue the objective of contributing to sustainable development and to have particular regard to climate-change mitigation and adaptation.

For decisions governed by a designated NPS, section 104 of the Planning Act 2008 establishes the principal decision-making framework, subject to statutory exceptions.

4. Examination, Participation and Environmental Protection

The NSIP regime combines infrastructure delivery with procedural safeguards. Before submitting an application, developers undertake statutory pre-application consultation. Once accepted, interested persons can participate in the examination.

Environmental assessment is especially important. Major infrastructure proposals may require detailed consideration of biodiversity, climate impacts, habitats, landscape effects, heritage and cumulative environmental consequences.

Legal challenges to DCO decisions normally proceed through judicial review. Section 118 of the Planning Act contains specific provisions concerning challenges to orders and decisions. A 2024 independent government review described DCO judicial review as an important mechanism while examining how delays from unsuccessful challenges might be reduced without undermining access to justice.

5. Case Law – R (Friends of the Earth Ltd) v Heathrow Airport Ltd [2020] UKSC 52

Facts: The Secretary of State designated the Airports National Policy Statement (ANPS) in 2018, supporting a third runway at Heathrow. Environmental organisations challenged the ANPS, arguing, among other matters, that the Government had failed properly to consider commitments under the Paris Agreement.

Legal Issue: Whether the failure alleged in relation to the Paris Agreement made designation of the ANPS unlawful under the Planning Act 2008.

Judgment: The Supreme Court unanimously allowed Heathrow Airport Ltd’s appeal. It concluded that the Government had not acted unlawfully on the relevant statutory grounds when designating the ANPS.

Legal Principle/Ratio Decidendi: The legality of an NPS must be determined according to the statutory requirements governing its designation. The Planning Act also distinguishes the policy-setting NPS stage from the later project-specific DCO assessment.

Significance: The judgment demonstrates how climate policy, environmental assessment and infrastructure policy interact within the NSIP framework.

6. Case Law – R (Save Stonehenge World Heritage Site Ltd) v Secretary of State for Transport

Facts: The A303 Stonehenge road scheme, involving road widening and a roughly 3 km tunnel, was treated as an NSIP. The original approval was quashed, but the Secretary of State subsequently redetermined the proposal and granted a DCO in 2023.

Legal Issue: The subsequent litigation concerned whether the redetermination had lawfully addressed relevant environmental and heritage considerations.

Judgment: The Court of Appeal upheld the redetermination. The Supreme Court later refused permission to appeal in January 2025, stating that the application did not raise an arguable point of law.

Legal Principle/Ratio Decidendi: NSIP decisions remain subject to public-law requirements, including lawful consideration of relevant matters, procedural fairness and rational decision-making.

Significance: Stonehenge illustrates the tension that the NSIP system must manage between national infrastructure objectives and protection of internationally important heritage and environmental interests.

7. Conclusion

The NSIP system provides a specialised national mechanism for authorising major UK infrastructure. Through DCOs, National Policy Statements, consultation, examination, environmental assessment and judicial review, the Planning Act 2008 seeks to combine efficient infrastructure decision-making with accountability and environmental protection. Case law confirms that national importance does not remove projects from legal scrutiny; rather, major infrastructure decisions must comply carefully with the statutory framework and general principles of public law.