Following a long running legal case, the UK’s Supreme Court ordered the UK Government to produce a new air quality plan to combat air pollution (in this instance primarily nitrogen dioxide from transport emissions). This unanimous decision of the Supreme Court, made on 29 April 2015, is fascinating from so many legal perspectives but ultimately what weighed very heavily on the court was (1) the recognition of “the real and continuing danger to public health”, about which (2) the court had its own responsibility to act in the public interest.  

The Supreme Court had to step in

In short the case involved breach by the UK of its obligations under an EU Directive on ambient air quality and cleaner air for Europe 2008 (the “Directive’) relating to nitrogen dioxide in air. Pollution from nitrogen dioxide in large urban areas, has been a known issue for some time (interestingly this judgement came the day after a World Health Organisation report which estimated the cost to Europe of the health impacts and mortality from air pollution was £1.03trn in 2010). Also the Department of the Environment, Food and Rural Affairs (“DEFRA”) accepted that the UK was in breach in respect of nitrogen dioxide and that in real terms the breach was becoming worse. DEFRA also accepted that new measures had to be considered by the Government and that a new plan to combat this was required (which would need to be submitted to the EU Commission). 

The Supreme Court recognised that in normal circumstances were a responsible public authority, such as DEFRA, to admit breach of a legal obligation and be willing to take steps to comply, the Court might think it right to accept a suitable undertaking from the public authority rather than put the authority under a mandatory order. However, in this instance, the Secretary of State for DEFRA was not in a position to give such an undertaking (given the restrictions imposed because of the then election period etc.) This could not have been an easy decision for the Supreme Court but unanimously the Court made an order that the Secretary of State prepare new air quality plans, to contain a defined timetable, and to deliver such new plans to the EU Commission by 31st December 2015 at the latest.  


The action was brought by ClientEarth, an environment justice foundation, against DEFRA in 2011. It involved earlier proceedings in the lower court and the Supreme Court, and referral to the Court of Justice of the European Union. In its various submissions ClientEarth stated that the original plans submitted by the UK were not ambitious enough to tackle the pollution issue, emphasising the fact that several city zones in London, Manchester, Glasgow and Cardiff would not meet targets until after a 2010 deadline, and some zones in London and Birmingham would not meet pollution targets until 2030.  

Not just a UK problem

The problem of non-compliance is not the UK’s alone, data from 2013 showed that 17 Member States were exceeding the hourly mean value of nitrogen dioxide.

Emissions from diesel vehicles

A reason cited before the Supreme Court for why the original plans to combat this pollution was due to unexpectedly higher emissions of nitrogen dioxide from diesel vehicles. Submissions were made on behalf of DEFRA that European vehicle emission standards were expected to deliver reductions in such emissions but real world emission performance of the vehicles turned out to be higher than expected from the regulatory test cycle.


We can expect to see a great deal of work being undertaken and promoted in the new plan. London has already consulted (October 2014) on the potential introduction of an “Ultra Low Emission Zone” from 2020. Traffic planning and management, pricing of congestion, emission, parking and other economic and fiscal measures may be considered. Of course this is not simply a matter for the UK. The public health issues do not respect geopolitical boundaries. They are enormous and increasing measured issues. They constitute one of the major drivers for change in the transport sector. We will be writing further on this in the near future.

To view the judgment, please click here.