Legal challenge filed against second runway at Gatwick Airport

It comes after Transport Secretary Heidi Alexander was put on legal notice by the group earlier this month following the decision to grant development consent for the expansion.

CAGNE says the impact of the expansion on climate change has not been properly assessed, and as a result development consent should not have been granted. 

Plans for the expansion were submitted in July 2023 and involve the repurposing of the current back-up runway at Gatwick Airport, allowing it to operate alongside the main runway. It is understood that the extra capacity will result in more than 100,000 extra flights per year by the late 2030s.  

Following an examination period, the plans were granted development consent in September 2025 – a decision which CAGNE says was flawed.  

The group says there are number of gaps in the environmental assessment of the development. These include a failure to properly evaluate the significance of inbound flight emissions and a failure to assess the effect of non-carbon dioxide emissions on the climate.  

CAGNE also argues that plans for the expansion wrongly rely on the Jet Zero Strategy (JZS), which is based on ambitious scenarios for the development of the aviation industry. The JZS assumes significant improvements in areas such as fuel efficiency, beyond current technology. 

CAGNE sent a pre-action protocol letter to the Transport Secretary at the start of October 2025 calling for the decision to grant development consent to be reversed. 

Now, the group has filed a judicial review claim against the decision on the following grounds:

• Flawed approach to calculating the significance of greenhouse gas emissions and/or failure to provide adequate reasons. 
• Error of law in the treatment of greenhouse gas emissions from international inbound flights. 
• Error of law in the treatment of non-carbon dioxide emissions.  
• Failure to take into account material risks in relation to the Jet Zero Strategy (JZS) and/or comply with the duty to make enquiries and/or irrational approach to the JZS.  
• Error of law in relying extensively on the JZS, which is itself unlawful.  
• Unlawful failure to weigh noise harms in the planning balance.  
• Unlawful requirement concerning wastewater treatment. 

Sally Pavey, chair of CAGNE, said: 

“The only guarantees Gatwick offered were significant increases in noise and more pressure on our sewage system, whilst increasing global warming to allow a huge increase in seasonal leisure flights exporting sterling out of the UK purse.  

“It is absolutely shameful that residents are forced to take legal action to hold a government to account. Months were spent examining the Gatwick submissions and yet a government can just ignore the outcome for refusal and grant unsustainable growth at any price to the local environment and the planet.  

“To build a brighter future you must look to what is sustainable, to what legacy we wish to leave future generations. One that increases global warming per Gatwick flight, that costs less than a train fare to London, or one that presents a sustainable future for all.” 

Leigh Day solicitor Julia Eriksen, who represents CAGNE, said: 

“The impact of a second runway at Gatwick Airport will undoubtedly be significant, and a thorough evaluation of the effects of this on the environment should be a key part of any proposal. However, our client says that the environmental impact has not been properly assessed, and that development consent has been granted despite a number of flaws in the planning application. After calling on the Transport Secretary to revoke development consent in a pre-action letter, CAGNE is now pursuing a judicial review challenge.”