Heathrow will argue in the supreme court this week that its proposed third runway would only ever be built in accordance with Britain’s climate commitments, as it seeks to overturn a court of appeal verdict that stopped the airport’s expansion plans. A two-day hearing starts on Wednesday which could allow Heathrow to proceed once more with building an additional runway. The expansion plans were approved in principle by parliament in 2018, under Theresa May’s government. Legal action by climate campaigners initially failed to force a judicial review. However, in a landmark judgment, the court of appeal ruled in favour of the case brought by the environmental litigation charity Plan B and Friends of the Earth. Judges found that ministers had failed to take adequate account of Britain’s climate commitments under the 2015 Paris climate agreement when drawing up the aviation national policy statement (ANPS) which permitted Heathrow expansion. The new government under Boris Johnson, a long-time opponent of the third runway, accepted the court ruling in February, leaving Heathrow to challenge it alone. The airport will argue that the runway will be bound to comply with Britain’s carbon targets when it seeks to obtain planning permission, regardless of whether the then transport secretary, Chris Grayling, adequately took account of the 2015 Paris climate agreement. The hearing will be conducted by video conference because of Covid-19 restrictions, and streamed live online. The verdict is not expected to be delivered until at least January. Tim Crosland, the director of Plan B, said the government could “at least see a problem in admitting it’s not taking the Paris agreement seriously, given that maintaining the Paris temperature limit is vital to our collective future … Heathrow Airport Limited, however, has no such concerns.” A Heathrow spokesperson said the airport fully expected to be held to account over climate obligations through the planning process, and that the ANPS made clear that approval for its runway “would be refused” if it had a material impact on the UK’s ability to meet its carbon reduction obligations. ”We’re appealing to the supreme court to allow this thorough planning process to proceed as it was designed. “Given the timescales required to deliver complex infrastructure of this scale in the UK, it’s critical that we get on with laying the groundwork today for future operations that will be essential for a successful global Britain in the decade after Brexit,” they added. The battle for expansion comes despite the pandemic leaving Heathrow with only a fraction of its normal air traffic and requiring just one runway to operate. The Unite union is balloting for a strike over plans by Heathrow to impose pay cuts of up to 20% on long-serving workers, which the airport has defended as a means to preserve jobs. John McDonnell, the Labour MP for the neighbouring Hayes and Harlington constituency, accused Heathrow of exploiting the pandemic to reduce wages, adding: “There is no excuse for the company imposing permanent wage cuts when we know that this crisis is temporary.”