Is Heathrow’s third runway finally taking off?

Airplane near the terminal in an airport Print publication


In a ruling handed down this week, the Supreme Court has removed a legal block preventing the development of a third runway at Heathrow Airport.

The legal claim brought by environmental campaign groups Friends of the Earth and Plan B sought to challenge the legality of the government’s National Policy Statement on airport capacity, which is the framework against which any future application for consent for a third runway will be assessed.

Although the claim raised numerous arguments, the most significant alleged that the government had failed to consider the Paris Agreement on climate change in reaching its decision on the National Policy Statement. The Paris Agreement seeks to reduce greenhouse gas emissions and temperatures arising from global warming; it was ratified by the UK in November 2016 but not transposed into domestic law.

When making a National Policy Statement, the law requires the Secretary of State to issue reasons for the decision, which must, in particular, explain how the National Policy Statement takes account of existing ‘government policy’ relating to the mitigation of climate change. The claimants alleged that in failing to refer to the Paris Agreement, the Secretary of State’s decision to publish the National Policy Statement was unlawful.

There was no dispute that the National Policy Statement had not referred to the Paris Agreement, however, did the Paris Agreement, and ministerial statements concerning it, constitute ‘government policy’ which should be considered and explained in relation to the National Policy Statement? This argument had been rejected by the High Court but upheld by the Court of Appeal before being finally decided in the Supreme Court.

In a unanimous judgement, the Court found that the meaning of ‘government policy’ in the relevant statute had to be understood narrowly, and that the minimum standard for a policy is a clear, unambiguous statement devoid of relevant qualification. The Court found that treaty commitments, which continue irrespective of whether a particular government remains in office, do not constitute ‘government policy’ and do not have domestic legal effect unless transposed in to domestic law.

The Court also found that two particular ministerial statements on the UK’s approach to the Paris agreement did not meet the minimum standard necessary in order for the statements to be considered ‘government policy’ for the purpose of the issuing National Policy Statement. The statements were considered by the Court to be unclear and did not explain how the targets and goals of the Paris Agreement would be incorporated into UK law.

The Supreme Court’s judgement is concerned with the government’s compliance with the law as it stood when the National Policy Statement was made in 2018, not about whether or not the government’s preference to build a third runway at Heathrow was (or remains) a good decision. Nevertheless the expansion of aviation could be perceived by some as being at odds with the government’s stated goal of achieving ‘net zero’. The judgment also raises a question over the importance of international environmental obligations, which may increasingly form the basis of environmental challenges in the light of Brexit. However, the following points are worth bearing in mind:

  1. The UK’s implementation of the Paris Agreement has not concluded. Although the Court found that an international agreement, and statements made in connection with it, did not require specific attention in the National Policy Statement, it noted the progress the UK continued to make in determining how to fully implement the Paris Agreement in UK (for example, in the forthcoming Aviation Strategy) which would need to be considered in the future.
  2. Heathrow will still need to apply for a Development Consent Order (DCO) to be able to build the runway. The Court felt that this process could ensure the runway complies with law and policy on environmental matters; in particular, the DCO process will require the Airport to comply with emissions targets as they stand when a decision on the DCO is made. The Court also noted that the law does not require a DCO to be granted if doing so would put the UK in breach of its international obligations.

Although this particular case has now reached the end of the appeal process in the UK’s courts, it is a reminder of the increase in ‘green litigation’ whereby activists pursue their objectives through the Courts as well as through more traditional means (as explained in our earlier article). So it would be unsurprising for new legal challenges to be brought as the runway proposals advance. Developers should also note that the Secretary of State did not defend the National Policy Statement in the Supreme Court – the successful appeal was run by Heathrow Airport; this is a timely reminder that developers will not always be able to rely on public bodies to defend their own decisions through repeated appeals.