If the UK continues to break the law, the European Commission could theoretically issue a letter of formal notice requiring it to remedy the situation. If previous breaches of EU environment rules are a guide, this could amount to tens of millions of euros per year.
Viviane Gravey, lecturer in European politics at Queen’s University Belfast, says any attempt to fine the UK would depend on whether it was politically expedient to do so. “Is it likely that the court would make an example out of the UK? If the commission would decide to go for fines for all the member states that are currently breaking the rules, and also because of the concern about the lack of dynamic alignment on environmental rules, then I think the UK would be included in that.”
But enforcing the fine would be difficult, if not impossible. “There have been so few fines anyway - in most cases they’re resolved before they get to the fine stage - and for the ones there have been we’re not actually sure that all the money has been collected,” says Gravey.
Simon Colvin, partner at law firm Weightmans, says the EU withdrawal agreements and government guidance are unclear on whether the CJEU could levy fines against the UK after Brexit but his assumption is that it cannot do so.
But the EU could put pressure on the UK in a different way. Gravey says there could potentially be a case under the Trade and Cooperation Agreement (TCA) between the UK and EU. The deal includes a commitment not to undermine existing environmental protections, although the EU shifted away from its initial position of full equivalence.
“It would not just be about the UK’s historical breaking of the EU rules but also about gradually building an even playing field between the UK and EU,” says Gravey. “There’s not much in the TCA when compared to the Court of Justice but it’s still more than you have in most, if not all, EU trade agreements. If one of the parties starts improving environmental protection to the level where it creates a loss of trade or investment because the other party is not going to spend, they can put in place temporary barriers to trade to even up the playing field.”
Gravey says the fact that the EU has twice started proceedings against the UK on the Northern Ireland protocol shows that it is still very willing to wield its legal tools. “The commission can just decide whether to take a case or not; nothing can force it do so. So it definitely can use its powers to start an infringement process quite politically.”
Colvin thinks legal action through the domestic courts is much more likely, with the CJEU ruling as a compelling piece of evidence. “We’ve reached a pause in the ClientEarth merry-go-round.... but the court has said that even the latest air quality plan is deficient. If the government does nothing then I can see ClientEarth going back to the courts. It would be quite hard for a UK court to say the plan is adequate when the Court of Justice has said it’s not. They might not accept everything the Court of Justice has said but the ruling is pretty damning.”
Colvin says the government could theoretically be held in contempt of court if it does not comply with a court’s ruling, although there is no obvious precedent for this happening.
There might also be a role for the UK's new Office for Environmental Protection (OEP), which will soon be responsible for holding the UK government accountable on the environment. As the Environment Bill stands, the OEP could bring environmental reviews of decisions by public bodies to the High Court, although it would not have the power to order them to be changed.
The ruling may also bolster efforts to tackle air pollution more directly in the Environment Bill. As it stands, the bill introduces a duty on the government to set at least two air quality targets by October 2022. But campaigners and some MPs want limits on fine particulate matter (PM2.5) in line with World Health Organization recommendations to be enshrined in the law itself.
Geraint Davies, a member of the Commons’ Environment, Food and Rural Affairs (EFRA) Committee who has pushed for stronger air pollution measures in the bill, says the ruling confirms that the government is putting people’s health at risk and illustrates the importance of a rigorous enforcement system to replace the European Commission and CJEU “now the public are outside of their protection”.
“It’s clear therefore that the Environment Bill needs to be strengthened to ensure that the Office for Environmental Protection has the power to sue and impose fines and that the new air pollution targets go further, with public health in mind.”
Gravey adds that eyes should not only be on the OEP but on environmental regulators in the devolved nations. “Scotland has been quite clear they want to keep pace with EU law and the jurisprudence of the Court of Justice with the Continuity Bill. So it could be that that case is pursued there but not in England or Northern Ireland. It is primarily an English case but it would be an opportunity for the devolved nations to show that they are ambitious on air pollution where England is not.
“Especially with Glasgow around the corner, we are in a situation where we have a lot of grandstanding on all sides,” says Gravey.
The international spotlight of the COP26 climate talks may indeed be the biggest spur to action. “What would be more acutely embarrassing than the government not doing enough in relation to air quality?” says Colvin. “I think this year in particular they would struggle not to do anything.”
A spokesperson for DEFRA said it was considering the judgment but noted that air pollution at a national level has reduced significantly since 2010. “We continue to work at pace to deliver our ambitious NO2 Plan and our 2019 Clean Air Strategy, which was praised by the WHO as ‘an example for the rest of the world to follow’.”