The fight against climate change has increased in the last years. The latest development was in the English Court of Appeal, which handed down a judgment on 27 February 2020, ruling the plans for the Heathrow third runway illegal, as they did not take into account the UK’s commitments to reduce greenhouse gas emissions under the Paris Agreement.[1]

Paris Agreement

The law regulating climate change is not a recent development. In 1992, the “United Nations Framework Convention on Climate Change” was introduced, which acknowledged that climate change was a pressing issue and aimed to stabilise greenhouse gas emissions through legislation.

More recently, the current Paris Agreement was implemented on 4 November 2016, with 55 countries ratifying the agreement, notably China, USA and India. The Agreement emphasizes that worldwide cooperation is necessary in order to combat climate change.

The Agreement aims to provide an effective and progressive response to greenhouse gas emissions. Article 2.1(a) contains the important objective of ensuring that the increase in global temperature is below 2°C, and eventually 1.5°.[2]

Heathrow Third Runway

The effect of the Paris Agreement was called into question before the Court of Appeal in relation to the proposed expansion of Heathrow airport. Currently, Heathrow is the busiest airport in the world and Europe, closely followed by Charles de Gaulle airport, which is estimated to overtake Heathrow.

In 2010, Heathrow made the proposal to add a third runway, in order to expand its capabilities and cement its position as a hub for trade. However, the expansion has been controversial from its conception, with Boris Johnson and David Cameron both opposing the expansion in their roles as Prime Minister.


One of the questions for the Court to answer was in relation to the Airports National Policy Statement (ANPS), containing the policy for the new runway. The ANPS is designated by the Secretary of State for Transport (Secretary of State). The question in relation to climate change and the Paris Agreement, focused on whether the designation of the ANPS was unlawful, as the Secretary of State did not have regard to climate change in light of the Paris Agreement.

The Court stated that the Secretary of State took legal advice that told him that he not only did not need to consider the Paris Agreement, but that he should not consider it. The Court held that this was a misdirection of the law, and it was “fatal” to the decision to designate the ANPS itself. The Secretary of State is required to consider government policy when designating an ANPS under section 5(2) of the Planning Act 2008.

The Court held that the government’s commitment to climate change under the Paris Agreement constituted government policy, and by choosing not to take the policy into account, the designation was not compliant with law.

The Court did clarify that it is not its job to assess political arguments, but only the lawfulness of the decision. It emphasised that the decision does not mean that there will never be a runway, but only that the government has an opportunity to reconsider the ANPS.

What effects could this have?

The British government has said that it will not appeal the decision, evidence again of the reticence for the project. It is for Boris Johnson to decide whether to re-consult on the plans, or whether to use this decision as reasoning to scrap the plans. There are strong arguments to continue the project in order to boost industry and reinforce Britain’s position as an aviation hub.

However, the decision may mean that other aviation projects may have to reconsider their plans to ensure that they address any policy for climate change. This may prove difficult for certain industries, where it is very difficult to be zero-carbon, and could be a difficult obstacle to further projects.

Furthermore, it now may be the case that when planning large projects such as this, legal costs will have to be taken into account in order to defend environmental challenges. Other large projects could see similar cases being brought based on this reading of the Paris Agreement.

Importantly, the decision has held that the Paris Agreement temperature targets are not aspirational, but instead are fixed targets to meet, and must be taken into account when planning large projects. It sends a clear message to the rest of the world about the importance of climate change.

Written by Francesca Bexon

[1] R v Secretary of State for Transport [2020] EWCA Civ 214