The UK Court of Appeal has dismissed a legal challenge by local campaign groups against Gatwick Airport's second runway plans, removing the last major judicial obstacle to a £2.2 billion expansion that will add roughly 100,000 flights a year at Britain's second busiest airport. The ruling, delivered on 4 August 2026, upholds the earlier High Court decision of Mr Justice Mould, who in June rejected two claims for judicial review — a legal process that lets courts check whether a government decision was made lawfully — of Transport Secretary Heidi Alexander's development consent order (The Guardian).

Alexander approved the Gatwick scheme on 21 September 2025. The project does not involve building an entirely new runway. Instead, it repositions the airport's existing emergency runway slightly and brings it into routine use for short-haul passenger aircraft. Gatwick expects the second runway to be operational as early as 2030 (The Guardian).

The legal challenge was brought by Peter Barclay, chair of the Gatwick Area Conservation Campaign, and the group Communities Against Gatwick Noise Emissions. They argued that the Department for Transport had not properly assessed the scheme's climate impact when granting development consent. The case, heard in the High Court from 20 January 2026, considered both the Gatwick Second Runway scheme and the Heathrow North West Runway scheme against factors including international connectivity. Mr Justice Mould dismissed both claims on 23 June 2026, ruling the approval lawful (Reuters; Judiciary UK).

Campaigners then escalated to the Court of Appeal. That court has now dismissed the challenge, confirming that the August ruling closes the judicial avenue. Barclay said he was disappointed with the outcome (The Guardian).

The government has paired the Gatwick approval with a parallel commitment on aviation emissions. It says it is investing more than £219 million in green fuel production aimed at cutting the sector's carbon footprint. Alexander stated that the expansion would bring around 13 million more passengers and 100,000 more flights annually (The Guardian).

The Gatwick ruling arrives alongside a parallel legal clearance for Luton Airport's expansion. Luton Rising, the council-owned company behind Luton airport, announced that all legal challenges to its expansion plans had been cleared. The UK Supreme Court dismissed any final possibility of appealing a High Court ruling from November 2025 that upheld Alexander's signoff on plans to increase Luton's annual capacity from 19 million to 32 million passengers by the mid-2040s. Luton's owner said the expansion would create up to 11,000 new jobs and generate up to an additional £1.5 billion in annual economic activity (The Guardian).

The broader context here is a sustained tension between the UK government's airport expansion policy and its legally binding climate commitments. Both the Gatwick and Luton approvals rest on a policy framework in which the government weighs aviation growth against projected improvements in sustainable aviation fuel — lower-carbon alternatives to conventional jet fuel — and operational efficiency. The £219 million green fuel investment is the concrete fiscal lever the government has attached to that trade-off. Whether that investment scales fast enough to offset the emissions from 100,000 additional Gatwick flights and a near-doubling of Luton's passenger throughput is a question the courts declined to resolve, having accepted that the government's assessment process was lawful rather than that its conclusions were correct.

For infrastructure planners and aviation stakeholders, the twin legal clearances effectively end a multi-year period of regulatory uncertainty at two of London's major airports. Gatwick's operator can now proceed toward a 2030 operational target, and Luton's owner has an unobstructed path to a mid-2040s buildout horizon. The Climate Change Committee's carbon budgets — legally binding limits on UK greenhouse gas emissions set in five-year chunks — remain a non-judicial constraint. Future policy adjustments, carbon pricing mechanisms, or further political pressure could still alter the economic calculus of these expansions even if the legal path is now clear. Campaigners' failure in the courts does not eliminate the political risk that emissions trajectories could force a recalibration of expansion timelines further down the line.