By Michael Green and Paul Davies

The UK will need to revisit its strategy to improve air quality following a recent court judgment determining that the Government’s existing plans are insufficient.  With air pollution reportedly responsible for 9,500 premature deaths in London each year, according to a study commissioned by the Greater London Transport Authority and Transport for London, the implications of this judgment are likely to have significant impact on the country’s transport infrastructure.

 Ruling in favour of ClientEarth

ClientEarth, a non-profit environmental law organisation, has followed its success in defeating the UK Government in the Supreme Court (in April 2015), by quashing the UK Government’s new Air Quality Plan (AQP) in the English High Court. The Court ruled that the AQP published in December 2015, in response to ClientEarth’s original legal challenge, falls short of the prescribed minimum legal standard. The UK Government must now produce a revised AQP pursuant to the earlier order made by the Supreme Court.

The scope of the obligations that will need to be set out in a revised AQP could have far-reaching practical implications, particularly in the UK’s transport sector. 

What can we expect of the revised AQP?

The case has several significant implications. For example, in this latest case ClientEarth criticised the UK Government for solely focusing on the establishment of Clean Air Zones to combat air pollution. ClientEarth advocated that a more diverse, inclusive framework of initiatives including, for example, fiscal incentives targeting diesel cars, was required.

In response, the Department of Environment, Food and Rural Affairs (DEFRA) was keen to emphasise that the UK had already adopted a pivotal role in Europe “to secure more accurate, real world emissions testing for diesel cars.” This defence was met with limited success in the High Court and therefore it remains to be seen whether the next AQP will pioneer a shift towards greater restrictions on the use of diesel cars.

Further, the decision may invite scrutiny of the recent high-profile approval given by Theresa May for the expansion of Heathrow Airport. Already environmental organisations, including Greenpeace, have launched an appeal to help pay for a judicial review of Heathrow’s expansion. The evolution of a more stringent air quality framework may indeed serve to complicate how the expansion can be realised, as compliance with air quality standards becomes more challenging.


Following the ClientEarth ruling, the UK Government is under increased pressure to introduce an AQP which will realistically address its obligations to reduce Nitrogen Oxide (NOx) emissions. It is currently unclear what form this AQP will take, but we can expect ClientEarth to continue to monitor its development closely and continue to demand tough measures to improve air quality in the UK.

This post was prepared with the assistance of Ashleigh Humphries in the London office of Latham & Watkins.