In R (on the application of ClientEarth (No.2)) v Secretary of State for Environment, Food & Rural Affairs [2016] EWHC 2740 (Admin) the claimant ("ClientEarth"), an environmental organisation, applied for judicial review of the defendant's (the "Secretary") Air Quality Plan ("AQP") which it considered to be below the standard required by EU Directive 2008/50/EC (the "Directive") and the Air Quality Standards Regulations 2010 (the "Regulations") which brought the Directive into domestic law, under which the UK is required to limit levels of ambient nitrogen dioxide.

The Administrative Court allowed the judicial review. It found that the AQP was not sufficient for meeting the result required by the Directive. The court stated that under the Directive, the discretion of member states to select the measures for compliance was narrow and that the Secretary of State had placed too much weight on issues of cost and administrative convenience and had used too optimistic a model when preparing the AQP.

Key Points

  • Public bodies must give effect to EU Directives and corresponding domestic regulations in a manner that aims to actually deliver compliance with those laws. Whilst there is discretion to choose different methods of achieving compliance with the nitrogen dioxide limits, that discretion does not extend to developing plans which are not likely to achieve compliance.

  • Decision-makers should be wary of making decisions on the basis of projections which they regard as optimistic.

  • Public bodies should not place undue weight on cost factors when fixing target dates for compliance with binding EU obligations, where those obligations include an element of urgency.

  • Measures for complying with EU obligations, in order to be regarded as proportionate, need go no further than is required to meet those obligations.


In this case, ClientEarth sought an order quashing the AQP that the government issued in response to the earlier decision in R (on the application of ClientEarth) v Secretary of State for the Environment, Food and Rural Affairs [2015] UKSC 28. In that case, the Supreme Court found that the UK was in breach of Article 13 of the Directive. The Directive sought to regulate public exposure to nitrogen dioxide, a gas that has "an effect on mortality equivalent to 23,500 deaths annually in the UK" according to the Department for the Environment, Food and Rural Affairs. As a result of this breach, the Supreme Court ordered the Secretary to issue an AQP as required by the Directive. The resultant AQP's emissions projections were modelled at five year intervals with compliance dates of 2020 outside London and 2025 in London.

ClientEarth commenced another judicial review in response to the government's published AQP. ClientEarth maintained that the new AQP failed to comply with domestic and EU law. In this case, ClientEarth submitted that the Secretary of State had erred in its understanding of the requirements of Article 23(1) of the Directive by making projections for 2020 and 2025. Article 23(1) states that periods where the limit value of nitrogen dioxide is exceeded should be kept "as short as possible." Further, the Secretary erred by giving consideration to matters like costs, political sensitivity and administrative concerns at the wrong stage of the decision-making process. ClientEarth also claimed that the modelling method chosen was mistaken.


Member State discretion under the Directive

The Secretary submitted that the wording in Article 23 of the Directive gave the UK government discretion to select the necessary measures to limit the amount of time that pollutant limits are exceeded. The court accepted that the Article gives some discretion to a Member State, but stated that it plainly narrows and constrains that discretion: "the Member State is obliged to ensure that the plans are devised in such a way as to meet the limit value in the shortest possible time."

The court rejected the assertion that the government could have regard to cost when fixing the target date for compliance or determining the route by which compliance can be achieved if one route were to be quicker than another. This flowed inevitably from the requirement in Article 23 to keep the exceedance period as short as possible.

The measures adopted, the court found, should be proportionate. That was understood to mean that they needed to do no more than was required to meet the target – and not that the requirement to meet the target could be weighed against other matters. This meant that the Secretary of State had to achieve compliance as soon as possible and via a proportionate route that reduced the pollution in the atmosphere as quickly as possible.

Five year plan

The emissions projections were made made at five year intervals, with the first one in 2020. The Secretary of State explained that this approach was adopted to "balance the additional cost of producing additional projections and the value of that data." The court was satisfied that the use of five year intervals was reasonable for routine monitoring of air quality, but it found that there was not "any evidence supporting the suggestion that five yearly cycles are sufficient when a Member State is faced with the urgent task of bringing its nitrogen dioxide readings back within the limits imposed by the Directive." The Secretary of State argued that to make annual projections would incur a cost of £50,000 and delay the production of the AQP by three months.

The court declared that cost and timing concerns were not relevant factors weighing against making annual projections. The court also found that the evidence pointed towards the government choosing 2020 as the date because 2020 seemed to be the earliest date the EU would move to issue fines. As a result, the government had taken the view that it would be better to spread the cost over the course of five years.

The court found that the Secretary had erred in selecting a date as distant as 2020 and that this did not meet the requirement under Article 23 to keep the exceedance period as short as possible. The problem of reducing nitrogen dioxide levels was urgent and the plan to do so should have been primarily concerned with achieving compliance as soon as possible.

Modelling method

ClientEarth argued that the modelling method that the Secretary had used was overly optimistic. The method for calculating diesel emissions which the Secretary used, based on the "Euro 6" diesel emission standards, was in conflict with the empirical evidence available to the Secretary; the rate of emissions assumed by the Secretary was substantially lower than the correct rate. If "Euro 6" cars emitted at the actual higher rate, then the number of zones with emissions exceedances in 2020 would be higher than the number the Secretary estimated in the AQP.

A cabinet briefing document presented to the court showed that the Secretary of State knew that there were major uncertainties around the modelling and that more action would probably be necessary than was presented in the AQP. The court determined that to adopt a plan based on modelling which the government knew to be optimistic would breach the Directive and the Regulations.

Alternative means

The AQP relied primarily on the introduction or strengthening of clean air zones. ClientEarth argued that the Secretary of State had failed to properly consider other measures such as fiscal incentives, scrappage schemes and retrofitting schemes. The court rejected this argument, holding that the selection of methods for achieving compliance was a matter for the government to decide, so long as compliance was likely.


Courts are normally reluctant to interfere with high-level matters of policy where there are a number of competing considerations which need to be weighed by decision makers. In this case, however, the nature of the statutory scheme meant that the government was obliged to formulate policy so as to bring ambient nitrogen dioxide levels down in the shortest possible time. This meant that the court was more willing to delve into the merits of the decision than might normally be the case in judicial review proceedings.