Infrastructure Planning Blog

Today’s entry looks at the failed judicial review of the Gatwick Airport Development Consent Order (DCO).

Please fasten your seatbelts

This mammoth case had 12 grounds of challenge brought by two separate parties. None of those succeeded. Indeed, before reviewing each of these grounds, it’s useful to look at the court’s barbed language throughout the claims: Mr Justice Mould described the grounds as "without foundation", "fanciful", “not reasonably arguable”, “unsustainable”, and having lost all “sight of the essential factual and legal context of the decision”, with some arguments “go[ing] nowhere”. Big yikes!

The first alleged ground was that the Secretary of State failed properly to understand the Airports National Policy Statement (ANPS). As a reminder, the ANPS did not have ‘effect’ for the purposes of section 104 of the Planning Act 2008 in relation to Gatwick, but it was accepted by both the ExA and the Secretary of State that it was an ‘important and relevant consideration’ for the purposes of section 105 of the Planning Act 2008. The specific ground was that the policy of the ANPS was that expansion of Gatwick Airport presents a threat to the UK’s global hub status. This appears to be a complete misreading of the ANPS, which when read alongside other national policy supporting the policy to ‘make best use’ of existing runways, and was dismissed by the learned judge.

The second ground claimed that in determining the Gatwick DCO, the Secretary of State was under a duty to promote the policies and objects of the Planning Act 2008 and the Climate Change Act 2008, each of which share the common objective of mitigating climate change by reducing GHG emissions. This, too, appears to be an argument without merit and the judge recounts exactly what you’d expect: the Planning Act 2008 sets out a framework for making decisions, and established case law and practice has made means it is perfectly possible for individual planning decisions to be compliant with the overall carbon reduction targets.

The third ground (related to four of the other grounds) specifically related to the consideration of greenhouse gas emissions (GHG) in the context of the Environmental Impact Assessment (EIA) Regulations. One element of these claims was specifically an attack on the conclusion that expansion would give rise to moderate adverse effects on the environment, which were significant but that was inconsistent with the finding that the proposed development would be compatible with meeting net zero and relevant carbon budgets. Was there a contradiction? No, and we have known that since the High Court made its judgment on the Drax DCO project and Bristol Airport decision(s). The Institute of Environmental Management and Assessment Guidance which everyone uses itself draws a clear distinction between the significance of a project’s effects for the purpose of carrying out EIA and the materiality of those effects in relation to the UK’s ability to achieve its carbon reduction targets.

Another element was that emissions from inbound flights had not been assessed. For context, the standard international approach was to account for aviation emissions at the source location for both international and domestic flights. The claim here was that the Supreme Court’s judgment in Finch (which, as expected, is growing unwelcome arms and legs) required that assessment. This was given short shrift in a welcome finding, consistent with the conclusions of the Court of Appeal in the Luton Airport case. The court, the full passage of which is worth quoting in full, sets out that:

“It is clear from that analysis [in Finch] that circumstances may arise in which the decision maker undertaking EIA identifies a project as giving rise to a likely effect or effects which, acting reasonably, they nevertheless judge either (i) not to be capable of meaningful assessment; or (ii) to be capable of assessment only to a limited or qualified extent. Provided that in making that judgment, the decision maker has given proper consideration to the possibility of assessment, that does not amount to a failure to fulfil the requirements of the EIA Regulations.”

Similarly, the approach of taking a qualitative assessment of non-CO₂ emissions was perfectly reasonable. Another unwinnable argument was that the Secretary of State failed to carry out the requisite systematic and comprehensive assessment of the likely significant effects of the proposed development. Mr Justice Mould, looking intently at the claimant, whispers “there is nothing in this complaint”, and similarly concludes that “adequacy of proposed mitigation to monitor, manage and control the impact of GHG emissions from the proposed development is not a question of law for the court.”

The fourth ground was that the Secretary of State’s consideration of need and economic benefits was irrational. The specific allegation was that the decision letter overstated the level of economic benefit that would arise from expansion, and that the Secretary of State had not adequately addressed representations on this point. No dice, says the High Court: the Secretary of State “recognised the uncertainties, took the established policy position as her starting point and from the plethora of assessment evidence submitted for examination” and her conclusion was “rational and supported by proper, adequate and intelligible reasons”. The attempt to do forensic analysis of underlying evidence, without taking into account the full thrust of the reason, is unlikely to be a convincing argument.

The seventh ground, quite peculiar, related to Requirement 31 of the DCO which states that the commencement of dual runway operations cannot take place until either (i) Thames Water have confirmed that the existing wastewater treatment works can accommodate the additional flows from the airport; or (ii) on-site wastewater treatment works have been completed. The argument was that an obligation on GAL to have completed the physical works for provision of the wastewater treatment facility comprised in Work No. 44. There is no obligation to bring that facility into operation. In other words, the claimant appears to have been contending that a commercial operator would construct a significant piece of infrastructure, and then for presumably whimsical reasons, not operate it or that Thames Water would find it unviable to do so.

Mr Justice Mould enters stage right, “it was rational for the SST to take the view that neither of those risks was sufficient to warrant any amendment to the terms of requirement 31(9). In particular, I think it fanciful to contemplate that having invested in and completed construction of wastewater treatment works in the circumstances contemplated in requirement 31 and as agreed with TWUL, GAL would decide not to bring those works into active use for the purpose for which they were needed and provided”. The claim that there was impermissible tailpiece (Requirement 31 applies “unless otherwise agreed” with Thames Water) was also rejected because “the tailpiece does no more than to provide an element of flexibility in enabling TWUL as statutory undertaker to give its agreement to alternative means of achieving the evident purpose for which the requirement has been imposed”.

Overall, a welcome judgment. It does, however, evidence the fact that quite “fanciful” (to quote the court) claims continue to be made notwithstanding the pre-warning of “totally without merit” claims having more severe treatment. Both claimants had the cost caps protection of the Aarhus Convention.

On the subject of judicial review, in case anyone missed it, the Civil Procedure Rule (CPR) Committee’s minutes from their last meeting indicate that the Committee discussed procedural changes to provide greater speed to the NSIP judicial review process by introducing shorter timescales in the High Court for judicial review of DCOs. It was resolved by that Committee to reduce the timeframe for serving pre-permission documents (from seven to three days) and for filing and serving the detailed grounds of defence (from 35 to 28 days) would be included in the upcoming CPR amendment cycle. As the Luton Airport judicial review shows, failure to comply will lead to quite strict treatment by the courts. That is welcome. You will hear that no more is needed on judicial review but the Government is clearly of the view that further measures are required, and the system is being abused. Good.

This publication is intended for general guidance and represents our understanding of the relevant law and practice as at June 2026.  For more information see our terms & conditions.