In the final paragraphs of the judgement, the Court stated that “The Airport National Policy Statement is of no legal effect unless and until the Secretary of State has undertaken a review of it in accordance with the relevant provisions of the Planning Act 2008”.
On the 27th of February, the Court of Appeal blocked the attempts of the British government to build a third runway at the London Heathrow Airport by ruling in favour of the appellants in case R (on the application of Plan B Earth) v. the Secretary of State for Transport,  EWCA Civ 214. Giving judgment, the three-judge panel emphasised that their judgement was not concerned with the political and social disagreements caused by the issue, but with the legal aspect of it. The legal answer was that the governmental decision to build a third runway was made unlawfully.
The issues that the Court ruled on related to how the decision to implement NWR instead of ENR related to the Habitats Directive (EC Council Directive 92/43/EEC relating to the protection of natural habitats), the SEA Directive (EC Council Directive 2001/42/EC on the assessment of the effect of certain plans and programmes on the environment), particularly as to whether the Secretary of State breached the SEA Directive by failing to consider the Paris Agreement and the UK’s other commitments to climate change.
Judges said that the UK government, which supported the NWR (North West Runway) proposal over the ENR (Extended Northern Runway) in their Airports National Policy Statement (ANPS), had failed to take into account what impact the move would have on Britain’s commitments under the Paris Agreement, as it would lead to increased CO2 emissions from up to 700 more flights to and from the airport daily.
The Climate Change Act 2008 set a “carbon target” for the United Kingdom to reduce its greenhouse gas emissions by 80% from their level in 1990, by 2050. However, the “Climate Change Act 2008 (2050 Target Amendment) Order 2019” amended the target figure in the Climate Change Act from 80% to 100%. In 2015, the Paris Agreement brought about a stronger international commitment to mitigating climate change by restricting the increase in the global average temperature to “well below 2°C above pre-industrial levels and [to pursue] efforts to limit the temperature increase to 1.5°C above pre-industrial levels” and by creating a commitment to achieve net zero greenhouse gas emissions during the second half of the 21st century. The UK ratified the Paris Agreement on 17 November 2016.
When the government approves policies such as the one authorising the third runway, section 10(8) of the Planning Act 2008 requires it to “include an explanation of how the policy set out in the statement takes account of Government policy relating to the mitigation of, and adaptation to, climate change”. Yet, the Secretary of State for Transport did not address this issue in his explanation. The Court highlighted that it does not follow from the Planning Act or the SEA Directive that the Secretary of State was obliged to act in accordance with the Paris Agreement or to reach any particular outcome. The only legal obligation was to take the Paris Agreement into account when arriving at his decision. As the ruling reads, “[t]he Paris Agreement ought to have been taken into account by the Secretary of State (…) and an explanation given as to how it was taken into account, but it was not.”
In the final paragraphs of the judgement, the Court stated that “The Airport National Policy Statement is of no legal effect unless and until the Secretary of State has undertaken a review of it in accordance with the relevant provisions of the Planning Act 2008”. The airport’s authorities have said they would appeal to the Supreme Court. On the other side, groups fighting for protection of the environment have described the verdict as “an absolutely ground-breaking result for climate justice.” As that the ruling read that “it does not venture into the merits of expanding Heathrow by adding a third runway, or of any alternative project”, but that it was only concerned with the formal process of approval of the ANPS, such statements can be considered to be of propagandistic nature.
It is worth noting that the same day that the Court granted this appeal, it dismissed another one relating to the same events, in R (on the application of (1) Heathrow Hub Limited (2) Runway Innovations Limited) v. the Secretary of State for Transport,  EWCA Civ 213. In that case, the Appellant argued that the decision confined in the ANPS was not based on factual evidence and that the Secretary had breached Articles 102 and 106(1) TFEU by demanding a guarantee from the Heathrow airport that they would build the ENR if it were chosen.