1. Introduction

Nationally Significant Infrastructure Projects (NSIPs) are major infrastructure developments in England, such as large energy-generation projects, electricity networks, major transport schemes, ports, and certain water and waste projects. Their principal statutory framework is the Planning Act 2008. Development consent is generally granted through a Development Consent Order (DCO) following examination by the Planning Inspectorate and a decision by the relevant Secretary of State.

Judicial review provides a mechanism for challenging the legality of an NSIP approval. It is not ordinarily an appeal on the merits of the infrastructure project. The court examines whether the decision-maker acted within legal powers, followed mandatory procedures, considered legally relevant matters, complied with environmental obligations, and reached a decision that satisfies the applicable principles of public law. The current government guidance confirms that legal challenges to DCO decisions are governed by the Planning Act 2008 framework. (GOV.UK)

The importance of judicial review is particularly high for NSIPs because these projects can have significant consequences for energy security, climate change, biodiversity, heritage, property rights, local communities and public expenditure.

2. Statutory Framework

The Planning Act 2008 created a special regime for nationally significant infrastructure.

The process broadly involves:

identification of the project as an NSIP;

preparation and submission of the DCO application;

pre-application consultation;

acceptance of the application;

examination by an Examining Authority;

recommendation to the Secretary of State;

decision by the Secretary of State; and

possible judicial review.

The DCO can provide development consent and may also contain associated powers, including compulsory acquisition and provisions concerning infrastructure operation.

Because Parliament has established a detailed statutory process, courts generally expect applicants and decision-makers to comply carefully with statutory requirements.

3. Judicial Review under the Planning Act 2008

A particularly important provision is section 118 of the Planning Act 2008.

A person seeking to challenge the validity of certain DCO decisions must generally bring the challenge through the statutory judicial-review mechanism and within the prescribed time limit.

The principal questions are not:

"Was this the best infrastructure project?"

but rather:

"Was the decision legally made?"

Thus, judicial review focuses on legality rather than substitution of administrative judgment.

4. Principal Grounds of Judicial Review

An NSIP approval may potentially be challenged on several grounds.

A. Error of law

The Secretary of State may misunderstand or misapply the Planning Act 2008, a National Policy Statement, environmental legislation or another relevant statutory requirement.

For example, a decision-maker may incorrectly believe that a particular statutory obligation does not apply to the project.

B. Procedural unfairness

The examination and decision-making process must comply with statutory procedural requirements and basic principles of fairness.

Potential issues can include:

failure to consider representations;

failure to provide an affected party with a fair opportunity to respond;

reliance on significant new material without adequate opportunity for comment;

failure to follow prescribed examination procedures.

However, not every procedural defect will automatically invalidate an approval. The court must consider the relevant statutory framework and the significance of the alleged defect.

C. Failure to consider material considerations

The Secretary of State must take into account matters which Parliament has made relevant to the decision.

For NSIPs these may include:

relevant National Policy Statements;

environmental impacts;

climate considerations;

biodiversity;

heritage;

traffic and transport;

alternatives where legally relevant;

compulsory acquisition considerations;

consultation responses; and

other matters required by the applicable legislation.

The precise scope of relevant considerations depends upon the statutory framework governing the particular project.

D. Taking irrelevant considerations into account

Conversely, a decision can be unlawful if the decision-maker relies upon matters that the law does not permit them to consider.

The central question is whether the consideration is legally relevant and whether it materially affected the decision.

E. Irrationality

An NSIP approval can theoretically be challenged where the decision is irrational in the public-law sense.

The traditional formulation comes from:

Associated Provincial Picture Houses Ltd v Wednesbury Corporation [1948] 1 KB 223.

The threshold is high. A court does not normally interfere simply because it would have reached a different conclusion.

This is particularly significant for NSIPs because many decisions involve technical, economic, environmental and predictive judgments.

5. Environmental Impact Assessment

Environmental assessment is one of the most important areas of judicial review of major infrastructure approvals.

Where EIA legislation applies, the decision-maker must ensure that environmental effects are properly assessed before granting consent.

The Supreme Court's decision in R (Finch) v Surrey County Council [2024] UKSC 20 is particularly important.

Although Finch concerned ordinary planning permission rather than a DCO, its reasoning is highly relevant to judicial review of infrastructure approvals involving fossil fuels and climate impacts.

The Supreme Court held, by a 3–2 majority, that the environmental assessment for an oil-extraction project was unlawful because it failed to assess greenhouse-gas emissions arising from the subsequent combustion of the extracted oil. (Supreme Court UK)

The case demonstrates that courts may examine the legal scope of environmental assessment, rather than simply accepting the decision-maker's characterization of the environmental consequences.

Significance for NSIPs

For major energy infrastructure, the case reinforces the importance of identifying:

direct environmental effects;

indirect effects;

cumulative effects;

climate effects;

reasonably foreseeable consequences; and

the relationship between the project and downstream environmental impacts.

It therefore provides an important example of how an apparently technical environmental-assessment question can become a ground for judicial review.

6. National Policy Statements and NSIP Decisions

National Policy Statements (NPSs) are central to the NSIP system.

The decision-maker must apply the relevant statutory framework governing the NPS and determine how much weight should be given to it.

A judicial-review claim may arise where the Secretary of State:

misunderstands an NPS;

fails to apply a mandatory provision;

disregards relevant policy without adequate justification;

treats a policy as legally binding when it is not; or

fails to reconcile the decision with other statutory obligations.

The court does not normally undertake its own planning assessment merely because another interpretation might have been possible.

7. The Stonehenge DCO Litigation

One of the most important examples is:

R (Save Stonehenge World Heritage Site Ltd) v Secretary of State for Transport [2021] EWHC 2161 (Admin)

The litigation concerned the A303 Amesbury to Berwick Down project, an NSIP involving a road tunnel near Stonehenge.

The original DCO decision was challenged and quashed. The Secretary of State subsequently reconsidered the project and issued a new decision.

The second decision was again challenged.

The High Court's 2024 judgment records that the second claim was brought under section 118 of the Planning Act 2008 challenging the redetermination. (Bailii)

The litigation demonstrates several important principles:

an NSIP decision can be quashed where the statutory decision-making process is legally defective;

quashing does not necessarily end the project permanently;

the Secretary of State may be required to reconsider the matter;

a subsequent redetermination itself can be challenged;

courts distinguish between genuine legal errors and disagreements over planning judgment.

The later proceedings ultimately reached the Supreme Court on an application for permission to appeal. The Supreme Court refused permission in January 2025. (Supreme Court UK)

8. Material Considerations in the Stonehenge Litigation

The Stonehenge litigation is particularly valuable because it illustrates the problem of ministerial briefing and material considerations.

The Supreme Court's case summary records that the Court of Appeal concluded that ministers were not legally obliged to investigate whether their briefing documents contained all obviously material considerations. It also held that the World Heritage Convention did not impose an absolute prohibition on harm to the World Heritage Site. Permission to appeal was subsequently refused. (Supreme Court UK)

This demonstrates that judicial review does not transform the court into the original decision-maker.

The court asks whether the decision-making process was lawful, rather than conducting a fresh assessment of the merits of the infrastructure scheme.

9. NSIP Airport and Transport Projects

NSIP litigation has also arisen in relation to airport and transport infrastructure.

For example, Ross v Secretary of State for Transport [2020] EWHC 226 (Admin) concerned proposed development at Stansted Airport and the statutory NSIP framework. The case involved a judicial-review challenge to the Secretary of State's treatment of the development as an NSIP and the applicable approval process. (Bailii)

Such cases demonstrate that classification itself can become legally significant.

If a project falls within the statutory NSIP regime, it may be subject to a substantially different consent process from ordinary planning applications.

10. Development Consent Orders and Environmental Law

An important feature of NSIP judicial review is the interaction between the Planning Act 2008 and other environmental legislation.

Depending upon the project, relevant legal regimes can include:

Environmental Impact Assessment;

habitats and biodiversity protection;

protected species legislation;

water regulation;

climate legislation;

air-quality regulation;

heritage protection;

marine environmental regulation; and

compulsory acquisition law.

A DCO cannot simply be treated as an isolated planning document. Its legality may depend upon compliance with several interconnected statutory regimes.

11. Climate Change and NSIP Approvals

Climate change has become increasingly important in judicial review of infrastructure decisions.

For energy NSIPs, the decision-maker may need to consider:

greenhouse-gas emissions;

national carbon budgets;

decarbonisation policy;

energy security;

renewable-energy objectives;

lifecycle emissions;

environmental assessment requirements.

The Finch decision illustrates the potential legal consequences of failing to include legally required climate impacts within an environmental assessment. The Supreme Court emphasized that the statutory EIA regime required assessment of the project's direct and indirect significant effects, including effects on climate. (Supreme Court UK)

However, Finch should not be understood as establishing that every infrastructure project must automatically be refused because it has climate impacts. Its principal significance is concerning the legal adequacy of environmental assessment.

12. Judicial Deference and Technical Decisions

NSIP decisions often involve highly technical issues:

electricity-system modelling;

traffic forecasting;

engineering;

environmental science;

economic modelling;

energy security;

demand forecasts;

construction risks.

Courts therefore generally recognize that specialist decision-makers have a legitimate area of judgment.

This does not mean that technical decisions are immune from review.

The distinction is:

Court's role: determine whether the decision is legally rational and procedurally lawful.

Decision-maker's role: make the substantive technical and policy judgment entrusted to it by Parliament.

The Finch litigation illustrates this distinction. The courts below treated some EIA questions as involving evaluative judgment, while the Supreme Court ultimately resolved the legal scope of the EIA obligation differently. (Wiley Online Library)

13. Consultation and Participation

Consultation is particularly important in NSIP proceedings because affected communities and interested parties participate through a structured examination process.

A challenge may arise where:

statutory consultation was not undertaken;

consultation was materially misleading;

responses were not properly considered;

the decision relied upon significant material that affected parties had no fair opportunity to address.

Nevertheless, courts distinguish between a legal failure to consult and mere dissatisfaction with the quality or outcome of consultation.

14. Compulsory Acquisition

Many NSIPs involve compulsory acquisition of land.

Judicial review may therefore raise questions concerning:

statutory authority;

necessity;

proportionality;

human rights;

compensation;

alternatives;

identification of affected interests.

Where private property rights are significantly affected, the legality of the compulsory acquisition powers can become an important component of the judicial-review analysis.

15. Remedies

Where a court finds an NSIP approval unlawful, the principal remedy may be a quashing order.

A quashing order removes the legal effect of the unlawful decision and generally requires the decision-maker to reconsider the matter lawfully.

Other possible remedies can include:

declaration;

mandatory order;

prohibitory order;

interim relief where appropriate.

The practical consequence can be substantial.

A successful challenge may require:

reconsideration of the decision;

additional environmental assessment;

reconsideration of relevant representations;

correction of an error of law; or

a fresh decision.

The Stonehenge litigation demonstrates how an earlier decision could be quashed and subsequently subjected to a new determination. (Supreme Court UK)

16. Important Case Laws

17. Key Principles Emerging from the Case Law

Several broad principles can therefore be identified.

1. NSIP approvals are legally reviewable

The special statutory regime does not exclude judicial supervision.

2. Judicial review is concerned primarily with legality

Courts do not ordinarily decide whether an infrastructure project represents the best policy choice.

3. Environmental assessment must be legally adequate

Where legislation requires assessment of particular environmental effects, failure to undertake the required assessment can invalidate consent.

4. Ministers must comply with statutory requirements

Ministerial discretion is broad but remains bounded by legislation.

5. Technical expertise does not eliminate judicial review

Courts may defer to technical judgment where appropriate, but they remain responsible for determining questions of law.

6. Heritage considerations can be legally significant

The Stonehenge litigation demonstrates the potential importance of heritage obligations and international heritage considerations in DCO decisions.

7. A successful challenge does not necessarily prohibit the project

A quashing order commonly results in reconsideration, rather than a permanent prohibition.

18. Conclusion

Judicial review of NSIP approvals represents a critical constitutional mechanism for ensuring that major infrastructure projects are authorized according to law. The Planning Act 2008 creates a specialized framework intended to facilitate nationally significant development while imposing structured requirements concerning examination, environmental assessment, consultation and ministerial decision-making.

The courts generally avoid substituting their own planning or infrastructure preferences for those of the statutory decision-maker. Nevertheless, the cases demonstrate that errors of law, inadequate environmental assessment, failure to comply with statutory procedures, failure to consider legally material matters, procedural unfairness and irrationality can result in an NSIP approval being quashed.

The Stonehenge litigation demonstrates the importance of lawful ministerial decision-making and the possibility of redetermination following a successful challenge. The Finch decision demonstrates the increasing importance of climate impacts and the legal scope of environmental assessment. Together, these cases show that judicial review functions not as a second planning examination, but as a mechanism for maintaining legality, procedural integrity, environmental accountability and statutory discipline in the approval of nationally significant infrastructure. (Supreme Court UK)