First air quality, then Article 50: with two government defeats in two days the UK High Court has demonstrated that it is willing to make tough judgments on issues with significant political and policy ramifications.

Most of the attention will be on the High Court’s judgment that triggering Article 50 of the Lisbon Treaty (thereby starting the process by which Britain would leave the EU) must be endorsed by Parliamentary approval (for further discussion, see our legal update Brexit judgement: parliament is sovereign) and of course that decision has profound constitutional and political ramifications.

However, the judgment in ClientEarth (No.2) v SSEFRA, handed down the previous day, should not be overlooked for its importance. Not only will it have immediate and far reaching implications for UK government policy on urban emissions and air quality, but it also signals a willingness by the courts to hold government to account over whether its policies go far enough.

Under the Air Quality Directive 2008, the UK government is obliged to take steps to mitigate the harmful effects of air pollution (including from nitrogen dioxide emissions) by setting standards for, and taking steps to assess and manage, air quality. The government consulted on and published plans to meet its obligations under the Directive, but the NGO ClientEarth has argued, through litigation before UK and European courts, that these plans are inadequate.

The judgment of 2 November was the second time in 18 months that a UK court has agreed with ClientEarth’s view. On 29 April 2015 the Supreme Court ordered that the government revisit its plans in relation to the Air Quality Directive. The latest ruling has held that the government’s revised plan – drawn up in light of that earlier judgment – is also inadequate. The Prime Minister has told Parliament that the government does not intend to appeal this judgment and that it will enter into discussions with ClientEarth on timeframes for revising the plans. If no agreement can be reached, it is possible that the Court will impose a timetable for action on government.

Whatever the outcome of discussions, the likelihood is tighter controls on emissions in a shorter period and over a greater geographical range than the government's plans to date. This is likely to have a significant impact on a number of major industry sectors, including transport, infrastructure and energy, and important implications for the public sector and local authorities who may have to deliver the plans.

One important aspect of the ruling in the ClientEarth case is that it represents the court’s willingness to intervene not only where government has failed to act in accordance with its obligations at law, but where the court is of the view that national Government policy in respect of those obligations is inadequate. The latest ClientEarth judgment is not a one-off decision, but is the culmination of years of litigation on this subject. It makes an interesting parallel with the High Court's intervention in the Brexit debate, on the subject of Royal prerogative versus Parliamentary sovereignty, another case that might be characterised as a question of policy and politics.

As the government goes back to the drawing board on its air quality plans, businesses need to keep a close eye on the plans that will emerge and how these will impact commercial operations. Burges Salmon's market-leading environmental law team will continue to stay at the forefront of air quality and industrial emissions law and policy (see, for example, our briefing Clean Air Zones: The Experts' Views).