How does section 13 of the Planning & Infrastructure Act 2025 affect DCO challenges?

Together Against Sizewell C (TASC) has been denied permission to appeal to the Court of Appeal following the High Court’s rejection of the request for judicial review of a ministerial letter. The Court of Appeal (CA) ordered on 16 February 2026 that the application to appeal was totally without merit. 

What is the background context? 

1. In 2022, the Secretary of State (SoS) made the Sizewell C (Nuclear Generating Station) Order (“DCO”);
2. TASC applied for judicial review of the DCO in 2022, holding that the SoS had been wrong to regard the water supply as not being part of the same project as the power station, and if the projects were separate the SoS should have carried out a cumulative assessment of their effects. The High Court held that each ground was totally without merit, and permission to apply for judicial review was dismissed. The appellant then sought to appeal and the CA decided that neither of the grounds was arguable. The Supreme Court also refused permission to appeal;
3. In March 2025, TASC wrote to the SoS to ask them to revoke or vary the DCO using their powers under Schedule 6, Paragraph 3(1) and (7) of the Planning Act 2008. The issue raised was that overland flood barriers (OFBs), which might be needed to protect against flooding, were not assessed as part of the ‘project’ despite being supposably committed to in the Office for Nuclear Regulation’s (ONR) external hazards assessment report, prepared as part of the nuclear site licensing process, if climate change turned out to be worse than reasonably foreseeable;
4. The SoS responded that the DCO controlled the scope of the project and it was subject to the appropriate assessment, and if it became necessary to include OFBs the developer could make a change application. It was also not a justified exercise of the power under paragraph 3(7) of the Planning Act 2008;
5. TASC applied for a judicial review of this decision in 2025, for which permission was refused by the High Court in December 2025. The Court certified that the application was ‘totally without merit’;
6. In February 2026, TASC sought to appeal the High Court decision to the Court of Appeal, and we have set out the details of this and the decision below.

The 2026 Court of Appeal Decision

In its application for permission to appeal the High Court’s refusal, TASC argued that the High Court judge had supplied his own post hoc reasons to fill the gap in the Minister’s letter. The CA  responded that the judge had not been speculating about what was in the Minister’s mind and instead assessed for himself as he was entitled to do.

The CA highlighted that the claimant did not make out the case for ‘exceptional circumstances’ for which the SoS should use their powers to revoke or carry the DCO. On a more technical point, the CA held that that the power in Schedule 6 only arises where the SoS is satisfied that if the development were carried out in accordance with the DCO it would be in contravention of assimilated law. Since the DCO in this case would be the project without the OFB, it would not be in contravention of the Conservation of Habitats and Species Regulations 2017 if it were carried out.

The CA emphasised it was essential to read the relevant parts of the ONR report properly and as a whole. Installing OFBs was not a firm proposal that had been committed to in the report,  and would only be considered ‘if they should be required’, which on current projections by the interested party would not arise before the year 2120 when the climate change trajectory was better understood. 

The CA held there was no arguable ground for bringing the application for judicial review, it did not have real prospect of success and there was no other compelling reason for the appeal to be heard.  

Why didn’t section 13(1) of the Planning and Infrastructure Act 2025 apply to this case?

The CA noted that section 13(1) of the Planning and Infrastructure Act 2025  had not yet come into force, or in any event did not apply to the order from which the appellant seeks to appeal. This is a useful reminder that section 13(1) came into effect on 18 February 2026 (two days after the CA’s order). In terms of its scope, section 13(1) inserts text into the Senior Courts Act 1981 so that there is no right to appeal to the CA from a refusal of permission to apply for judicial review in a case within section 13 or section 118 of the Planning Act 2008 (relating to proceedings relating to national policy statements or development consent) if the High Court decides that the application for permission to apply for judicial review is totally without merit. As the DCO had become immune from further legal challenge under s.118 of the 2008 Act, the challenge before the CA related to the ministerial letter responding to TASC’s request to the SoS to revoke or vary the DCO using their powers under Schedule 6, Paragraph 3(1) and (7) of the Planning Act 2008 which therefore fell outside the scope of s13(1). Now that this provision is in force, it is likely to reduce the number of challenges made to decisions under sections 13 and 118 of the Planning Act 2008. 

Separately to this, the CA highlighted paragraph 17.3 of Practice Direction 52D of the Civil Procedure Rules which indicates the enhanced need for celerity in DCO challenges.

We have extensive experience in promoting DCOs and defending subsequent challenges made to granted DCOs, so please do contact Alex Minhinick if you have any queries.