1. Introduction

A Development Consent Order (DCO) is a statutory mechanism used in England and Wales for authorising certain Nationally Significant Infrastructure Projects (NSIPs), particularly major energy, transport, water, and infrastructure developments. The principal legislative framework is the Planning Act 2008.

Because a DCO may authorise compulsory acquisition, construction, environmental works, highways changes, and other substantial interventions, Parliament has provided a specialised system of examination and decision-making. Nevertheless, the grant of a DCO is not immune from judicial scrutiny. Judicial review provides a mechanism through which the legality of the DCO process and decision can be challenged.

Judicial review does not ordinarily permit the court to substitute its own planning judgment for that of the Secretary of State or examining authority. Instead, the court examines whether the decision-maker acted within statutory powers, followed the required procedure, took legally relevant matters into account, complied with environmental obligations, and reached a decision that is legally rational.

The distinction between the merits of infrastructure policy and the legality of the consent decision is therefore central.

2. Statutory Framework

The principal legislation is the Planning Act 2008.

Under the DCO regime:

the developer submits an application for development consent;

the application is accepted for examination;

an independent examination takes place;

the Examining Authority prepares a report and recommendation;

the relevant Secretary of State determines the application; and

a DCO is made if consent is granted.

A DCO can contain provisions concerning matters such as:

development authorisation;

compulsory acquisition;

rights over land;

highways;

protective works;

environmental mitigation;

requirements controlling subsequent development;

operation and decommissioning.

The Infrastructure Planning (Environmental Impact Assessment) Regulations 2017 may also become important where the project is subject to environmental impact assessment.

Other legislation can become relevant depending on the project, including the Habitats Regulations, the Equality Act 2010, the Human Rights Act 1998, and legislation relating to compulsory acquisition.

3. Statutory Judicial Review Under the Planning Act 2008

The Planning Act establishes a particularly important judicial review mechanism.

Under section 118 of the Planning Act 2008, a person may challenge the validity of a DCO through proceedings in the High Court.

The challenge is generally required to be brought within a short statutory time period. This reflects Parliament's objective of giving major infrastructure projects a relatively high degree of legal certainty once consent has been granted.

The statutory grounds broadly concern situations where:

the order was not within the powers of the Planning Act;

statutory procedural requirements were not complied with;

there was another legal error affecting the validity of the decision.

The court therefore examines the lawfulness of the decision-making process, rather than conducting a fresh planning inquiry.

4. Grounds of Judicial Review

A. Illegality

The first major ground is illegality.

A DCO decision-maker must correctly understand and apply the legislation governing development consent. If the decision-maker acts outside the powers granted by Parliament, the decision may be unlawful.

For example, illegality may arise where the Secretary of State:

applies the wrong statutory test;

misunderstands the scope of the DCO power;

fails to comply with a mandatory statutory obligation;

takes into account a factor that Parliament did not permit to influence the decision;

fails to consider a legally mandatory factor.

The traditional authority is:

Council of Civil Service Unions v Minister for the Civil Service [1985] AC 374

The House of Lords identified the classic categories of judicial review:

illegality;

irrationality;

procedural impropriety.

Although this case did not concern a DCO, its principles remain foundational to administrative judicial review.

5. Procedural Fairness

A DCO examination involves extensive participation by:

developers;

local authorities;

landowners;

statutory consultees;

environmental organisations;

affected residents;

other interested parties.

The decision-making process must comply with the statutory procedural framework.

Judicial review can therefore arise where there has been a serious procedural defect.

Examples include:

failure to comply with consultation requirements;

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

reliance on material without giving parties an opportunity to address it;

failure to follow the statutory examination procedure;

procedural unfairness in compulsory acquisition issues.

A major general authority is:

R v Secretary of State for the Home Department, ex parte Doody [1994] 1 AC 531

The House of Lords emphasised that fairness is context-dependent and that affected persons should generally have a meaningful opportunity to understand and respond to material relevant to the decision.

In the DCO context, procedural fairness must, however, be understood alongside the highly structured statutory examination process established by the Planning Act.

6. Irrationality and Unreasonableness

The second classic ground is irrationality.

The threshold is high.

The court does not ask:

"Would the court have reached the same planning decision?"

Instead, it asks whether the decision was so unreasonable or irrational that it falls outside the range of lawful decision-making.

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

The case established the traditional principle of Wednesbury unreasonableness.

In infrastructure cases, this principle is particularly significant because development consent frequently involves balancing competing considerations, including:

economic benefits;

energy security;

environmental impacts;

climate objectives;

landscape effects;

biodiversity;

transport;

housing;

local community impacts.

Courts generally recognise that such balancing exercises are primarily matters for the statutory decision-maker.

7. Judicial Review Does Not Become an Appeal on Planning Merits

One of the most important principles is that judicial review is not a merits appeal.

The court does not normally reconsider:

whether a wind farm should have been approved;

whether a road should have been constructed;

whether an energy project provides sufficient economic benefit;

whether a particular planning policy should receive greater weight.

The court instead asks whether the decision-maker's conclusion was legally available.

This principle is illustrated by:

R (on the application of Newsmith Stainless Ltd) v Secretary of State for Environment, Transport and the Regions [2001] EWHC Admin 74

The courts emphasised the distinction between reviewing legality and substituting judicial judgment for the planning judgment of the statutory decision-maker.

8. Failure to Take Relevant Considerations into Account

A DCO decision may be unlawful where the decision-maker fails to consider a matter that the law requires to be considered.

This is especially significant in large infrastructure projects because decision letters can involve enormous quantities of evidence.

Relevant considerations may include:

environmental impacts;

climate considerations;

relevant national policy statements;

alternatives where legally required;

biodiversity;

effects on protected sites;

compulsory acquisition impacts;

human rights;

equality considerations.

The key question is not whether every submission made by every participant was expressly mentioned.

Rather, the court asks whether the decision-maker lawfully addressed the matters that were legally material.

R (Friends of the Earth Ltd) v Secretary of State for Transport [2020] EWCA Civ 214

This litigation concerning the Airports National Policy Statement demonstrates the importance of understanding the statutory framework governing governmental infrastructure decisions and the legal relevance of climate policy.

9. Environmental Impact Assessment and DCO Judicial Review

Environmental assessment is one of the most important areas of DCO litigation.

Large infrastructure projects can require an Environmental Impact Assessment (EIA).

The EIA process is intended to ensure that significant environmental effects are properly identified, assessed, and taken into account.

Judicial review may challenge:

inadequacy of an Environmental Statement;

failure to assess a significant environmental effect;

inadequate consideration of alternatives;

defective consultation;

failure to consider cumulative effects;

inadequate mitigation analysis;

failure to provide sufficient environmental information.

The courts have repeatedly emphasised that environmental assessment is not merely a procedural formality.

10. Important Environmental Case: Champion

R (Champion) v North Norfolk District Council [2015] UKSC 52

The Supreme Court considered environmental assessment requirements in the context of planning.

The judgment is important for understanding how courts approach alleged procedural defects in environmental assessment.

The Court recognised that not every procedural defect automatically requires a decision to be quashed. The significance of the defect and its effect upon the decision-making process may be relevant.

This principle is particularly important in complex infrastructure cases, where parties frequently argue that an environmental assessment was legally defective.

11. Environmental Information and Alternatives

A recurring issue in infrastructure judicial review is whether the decision-maker had sufficient information to make an informed decision.

The EIA process requires environmental information to be gathered and presented so that the decision-maker can properly understand the project's environmental consequences.

In:

R (Friends of the Earth Ltd) v Secretary of State for Transport [2020] EWCA Civ 214

the Court of Appeal considered the relationship between climate policy and infrastructure decision-making.

The case illustrates an important distinction:

Political or policy disagreement does not automatically constitute legal error.

A claimant must generally demonstrate that the decision-maker misunderstood or unlawfully failed to apply a legally relevant policy or statutory requirement.

12. Climate Change Considerations

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

DCO projects may involve:

offshore wind;

electricity transmission;

gas infrastructure;

hydrogen infrastructure;

carbon capture;

airports;

roads;

ports.

A challenge may argue that the decision-maker failed to consider:

statutory climate obligations;

relevant climate policy;

greenhouse-gas emissions;

cumulative climate impacts.

However, courts distinguish between a legal requirement to consider climate change and an argument that the project should have been rejected because of climate change.

The former may be judicially reviewable; the latter may amount to a disagreement with the merits of the decision.

13. Habitats and Protected Sites

DCO projects may affect:

Special Areas of Conservation;

Special Protection Areas;

Ramsar sites;

protected species;

habitats.

The Habitats Regulations can therefore become central.

Where legally required, an appropriate assessment must be undertaken.

The courts have historically adopted a stringent approach to the protection of European sites.

R (Champion) v North Norfolk District Council [2015] UKSC 52

Although not itself a DCO case, it illustrates the Supreme Court's approach to environmental assessment and the consequences of procedural deficiencies.

European and domestic environmental law can therefore create additional layers of judicial scrutiny over major infrastructure consent.

14. Legitimate Expectation

A claimant may sometimes argue that a public authority created a legitimate expectation through a clear representation or established practice.

However, legitimate expectation is difficult to establish in complex planning and infrastructure decisions.

The courts distinguish between:

procedural expectations; and

substantive expectations.

The leading authority is:

R v North and East Devon Health Authority, ex parte Coughlan [2000] 3 All ER 850

The Court of Appeal recognised that sufficiently clear governmental promises may create enforceable expectations in appropriate circumstances.

In DCO proceedings, however, such arguments must be reconciled with the statutory planning framework. A representation cannot normally override Parliament's statutory scheme.

15. Human Rights Considerations

DCOs can interfere with property rights and therefore may engage:

Article 6 — fair hearing;

Article 8 — private and family life;

Article 1 of Protocol No. 1 — protection of property.

This becomes particularly important where the DCO includes compulsory acquisition.

The court may consider whether the interference is:

lawful;

directed toward a legitimate public objective;

proportionate.

R (on the application of Luton Borough Council) v Secretary of State for Transport [2008] EWHC 1978 (Admin)

Infrastructure decision-making involving major development illustrates the broader importance of lawful governmental decision-making where significant public and private interests are affected.

16. Compulsory Acquisition and Judicial Review

Many DCOs include compulsory acquisition powers.

The developer may seek authority to acquire:

land;

rights over land;

easements;

access rights.

Challenges can therefore focus on whether compulsory acquisition is justified and whether statutory requirements have been satisfied.

Typical issues include:

necessity;

proportionality;

availability of alternatives;

adequacy of negotiations;

identification of affected land;

human rights;

compensation.

The court will generally recognise the statutory decision-maker's judgment but will intervene where compulsory acquisition powers are exercised outside their lawful purpose.

17. National Policy Statements

National Policy Statements (NPSs) are fundamental to the DCO system.

They provide the policy framework against which major infrastructure proposals are considered.

Judicial review can therefore concern:

interpretation of an NPS;

failure to apply an NPS;

misunderstanding of an NPS;

failure to consider a mandatory policy requirement.

However, courts generally give considerable respect to the policy judgments contained within properly adopted national policy.

This reflects the constitutional division between:

policy formulation, primarily undertaken by Government and Parliament; and

legal review, undertaken by the courts.

18. Case Study: Heathrow Airport Litigation

One of the most significant modern infrastructure judicial review cases is:

R (Friends of the Earth Ltd) v Heathrow Airport Ltd [2020] UKSC 52

The Supreme Court considered the legality of the Airports National Policy Statement in the context of climate change.

The case is important because it examined the relationship between:

statutory planning frameworks;

governmental policy;

climate commitments;

infrastructure development.

The Supreme Court held that the statutory concept of government policy did not necessarily encompass every international commitment made by the United Kingdom.

The case demonstrates that judicial review of infrastructure policy depends heavily upon the precise wording and structure of the governing legislation.

19. Duty to Give Reasons

Reasons are particularly important in major infrastructure decisions.

The decision-maker should explain sufficiently why the application has been granted or refused and how significant competing considerations have been addressed.

However, the law does not require the decision-maker to respond individually to every argument.

The leading authority is:

South Buckinghamshire District Council v Porter (No 2) [2004] UKHL 33

The House of Lords held that reasons must be sufficient to enable the reader to understand the decision and why the decision-maker reached it.

This principle is highly relevant to DCO decisions because decision letters may involve numerous complex objections.

20. Materiality of Legal Errors

Not every mistake results in a successful judicial review.

The court may consider whether the alleged error was material.

The modern statutory framework also gives courts powers concerning cases where an outcome would have been substantially the same even without the identified error.

An important authority is:

R (Girling) v Parole Board [2006] EWHC 3421 (Admin)

The broader principle is that judicial review focuses on legal errors that matter to the lawfulness of the decision rather than technical imperfections having no meaningful relevance.

In major infrastructure litigation, therefore, the claimant generally needs to establish more than the existence of an imperfection.

21. Remedies

If a judicial review succeeds, the court may grant remedies such as:

Quashing Order

The court may quash the DCO or the relevant decision.

The matter may then return to the appropriate decision-maker for lawful reconsideration.

Declaration

The court may declare the legal position without necessarily quashing the entire decision.

Injunction

In appropriate circumstances, the court may restrain unlawful action.

Mandatory Order

The court may require a public authority to perform a legal duty.

The remedy depends upon the nature and seriousness of the legal error.

22. Why DCO Judicial Review Is Different from Ordinary Planning Appeals

The DCO system differs from ordinary planning permission.

A conventional planning decision may involve a local planning authority.

A DCO involves a national infrastructure regime with:

statutory examination;

specialist examining authorities;

national policy statements;

ministerial decision-making;

compulsory acquisition powers;

environmental assessment;

extensive public participation.

Consequently, judicial review operates within a highly structured statutory framework.

The court must respect the institutional role Parliament has assigned to the relevant decision-makers.

23. Judicial Deference in DCO Cases

The courts generally exercise restraint where the decision involves:

technical expertise;

economic assessment;

infrastructure planning;

environmental balancing;

national policy;

competing public interests.

This does not mean that decision-makers are immune from review.

Rather, the intensity of review may vary according to the nature of the question.

A pure question of law attracts strong judicial scrutiny.

A highly technical or policy-based judgment may receive greater judicial respect.

This is consistent with:

R (Daly) v Secretary of State for the Home Department [2001] UKHL 26

Lord Steyn explained the relationship between traditional Wednesbury review and proportionality, particularly where fundamental rights are involved.

24. Key Principles Emerging from the Case Law

The case law establishes several important principles:

25. Conclusion

Judicial review of Development Consent Orders is fundamentally a review of legality rather than planning merits. The Planning Act 2008 creates a specialised statutory framework for major infrastructure projects, but the Secretary of State and other decision-makers remain subject to the supervisory jurisdiction of the courts.

The most important grounds of challenge include:

illegality;

procedural impropriety or unfairness;

failure to consider relevant considerations;

irrationality;

breach of environmental assessment requirements;

failure to comply with habitats protection requirements;

failure to give adequate reasons;

breach of human-rights or proportionality requirements; and

unlawful exercise of compulsory acquisition powers.

The case law—from CCSU, Wednesbury, Doody, Porter, Champion, and Heathrow—demonstrates the constitutional balance involved. Courts ensure that major infrastructure decisions comply with Parliament's legal framework, while generally leaving questions of policy, technical assessment, and planning balance to the institutions entrusted with those responsibilities.

Thus, DCO judicial review acts as a legal safeguard for accountable infrastructure governance without transforming the courts into a substitute planning authority.