Development Consent Order (DCO) Appeal Procedures

1. Introduction

A Development Consent Order (DCO) is the main legal permission used for many Nationally Significant Infrastructure Projects (NSIPs) in England. It can authorise major projects such as electricity generating stations, offshore wind infrastructure, electricity transmission lines, pipelines, roads and other nationally important infrastructure.

The Planning Act 2008 creates a special system for DCO applications. Importantly, a DCO does not normally have an ordinary planning appeal like a normal planning application. Instead, challenges to a made DCO are generally brought through judicial review. Section 118 of the Planning Act 2008 provides the specific legal challenge procedure. (Legislation.gov.uk)

2. DCO Decision-Making Process

The DCO process generally involves:

Pre-application consultation

Submission of the DCO application

Acceptance of the application

Examination by an Examining Authority

Recommendation to the Secretary of State

Decision by the Secretary of State

Making and publication of the DCO

Judicial review, where a person wants to challenge the legality of the decision

The examination stage is important because affected persons, local authorities and other interested parties can present evidence and make representations before the final decision.

3. Is There a Normal Appeal Against a DCO?

The answer is generally no.

A person cannot normally appeal a DCO decision simply because they disagree with the Secretary of State's planning judgment. Instead, the Planning Act provides a judicial review route.

Section 118 states that proceedings questioning an order granting development consent must be brought by judicial review. The claim must normally be filed within six weeks beginning with the day after publication of the order, or, where later, publication of the statement of reasons. (Legislation.gov.uk)

This short time limit is important because major infrastructure projects need legal certainty.

4. Grounds for Challenging a DCO

Judicial review is concerned mainly with the legality of the decision, rather than asking the court to decide whether the project is a good or bad idea.

Possible grounds include:

illegality – the decision-maker misunderstood or exceeded its legal powers;

procedural unfairness – an important procedural requirement was not followed;

failure to consider relevant matters;

consideration of irrelevant matters;

failure to give legally required reasons; and

irrationality or unlawfulness in the decision-making process.

Therefore, the court generally does not substitute its own planning judgment for that of the Secretary of State.

5. Six-Week Limitation Period

The six-week period is one of the most important features of DCO challenges.

Under section 118:

a DCO may be challenged within six weeks;

a refusal of development consent may also be challenged within six weeks;

certain decisions concerning acceptance of an application can also be challenged within six weeks; and

certain decisions concerning changes or revocation of a DCO have their own six-week challenge periods. (Legislation.gov.uk)

This strict timetable reflects the public importance of NSIPs and the need to avoid indefinite uncertainty.

6. Case Law: Barclay v Secretary of State for Transport

A very recent example is Barclay & Anor v Secretary of State for Transport [2026] EWCA Civ 1040.

The case concerned the Gatwick Airport DCO. The Secretary of State had made a DCO authorising improvements to the northern runway and associated airport development. The claimants brought judicial review proceedings under section 118 of the Planning Act 2008. (Bailii)

The case demonstrates an important point: even after the Secretary of State makes a DCO, affected parties can challenge the lawfulness of the decision through judicial review.

It therefore provides a useful modern example of the DCO challenge mechanism.

7. DCO Requirements and Appeals

There is another type of appeal connected with a DCO.

A DCO may contain requirements controlling how the authorised development must be carried out. Sometimes a requirement must later be discharged by a local planning authority or another designated authority.

Where the promoter disagrees with a decision concerning the discharge of a requirement, the DCO may provide an appeal mechanism.

Government guidance explains that a DCO can use either:

a modified version of the ordinary planning appeal procedure under sections 78 and 79 of the Town and Country Planning Act 1990; or

a bespoke appeal mechanism written into the DCO itself. (GOV.UK)

This is different from challenging the DCO itself.

8. Judicial Review vs Requirement Appeal

It is useful to distinguish the two:

Thus, the word “appeal” can be misleading. A DCO has different mechanisms depending on what exactly is being challenged.

9. Recent Procedural Changes

The Planning and Infrastructure Act 2025 has introduced changes concerning judicial review of DCO decisions. The legislation provides for changes to the permission stage, including an oral permission hearing in the High Court for relevant DCO judicial review cases. Where permission is refused and the case is certified as “totally without merit,” the new framework removes a further appeal to the Court of Appeal. These provisions require commencement regulations before taking effect. (Legislation.gov.uk)

This shows that Parliament continues to adjust the DCO challenge system to balance access to justice with the need for speedy delivery of nationally significant infrastructure.

10. Importance for Energy Projects

DCO appeal and challenge procedures are particularly important for energy infrastructure.

Large offshore wind projects, electricity transmission infrastructure, pipelines and generating stations can involve major environmental, land, community and economic interests.

The DCO system therefore attempts to balance:

infrastructure development + environmental protection + public participation + legal accountability + certainty for investors.

The short judicial review period helps provide certainty, while judicial review ensures that the Secretary of State remains within the law.

11. Conclusion

The DCO appeal procedure is different from an ordinary planning appeal. Once a DCO is made, the principal method of challenging its legality is judicial review under section 118 of the Planning Act 2008, normally within a strict six-week period. (Legislation.gov.uk)

At the same time, individual decisions about DCO requirements may be subject to specific appeal mechanisms written into the DCO.

Cases such as Barclay v Secretary of State for Transport demonstrate that DCO decisions remain subject to judicial supervision. The overall system therefore seeks to provide both legal accountability and certainty for nationally significant infrastructure projects.