Wider scope for intervention in environmental claims

England and Wales

With environmental and climate change issues moving to the top of the corporate and political agenda, the High Court’s latest decision on Aarhus Convention claims paves the way for greater engagement by interested parties in environmental claims, including judicial review.


The Aarhus Convention 2001 (or, more accurately, the United Nations Economic Commission for Europe Convention on Access to Information, Public Participation in Decision-Making and Access to Justice in Environmental Matters) has three core components, all relating, as the name suggests, to environmental matters:

  1. access to environmental information;
  2. public participation in environmental decision-making processes; and
  3. access to justice, providing rights to challenge decisions made in breach of the first two components, or in contravention of national law relating to the environment.

The relevant judicial procedures must also provide adequate and effective remedies and be fair, equitable, timely and “not prohibitively expensive”.

The UK’s history with the Aarhus Convention is long and complex, and beyond the scope of this update. One point of contention has been the extent to which the UK has addressed the requirement for proceedings not to be prohibitively expensive. The current position is reflected by the latest update to Rule 45 of the Civil Procedure Rules (CPR 45), effective from 1 October 2019, which limits qualifying claimants’ costs exposure in Aarhus Convention claims to £5,000 for individuals or £10,000 in all other cases. Defendants’ exposure is capped at £35,000.

For the purposes of CPR 45, Aarhus Convention claims are limited to judicial review or statutory review claims brought by members of the public that are within the scope of the Aarhus Convention (as summarised above). To benefit from the standard limits on costs, claimants and defendants must demonstrate that they meet certain requirements, including the provision of information relating to the claimant’s financial resources.

The court has the power to vary the costs limits (on application by one of the parties) where it is satisfied that: (a) to do so would not make the costs of the proceedings prohibitively expensive for the claimant (taking into account specified factors); and (b) in the case of a variation which would reduce a claimant’s maximum costs liability or increase that of a defendant, without the variation the costs of the proceedings would be prohibitively expensive for the claimant.

Whilst the position on claimants and defendants is expressly addressed in the CPR, it is silent on the position of interested parties, i.e. “any person (other than the claimant and defendant) who is directly affected by the claim”.

Are interested parties entitled to costs in Aarhus Convention claims?

In July last year, the Court of Appeal confirmed that where a claimant has issued and served proceedings against a number of parties, that claimant may prima facie be liable for more than one set of reasonable and proportionate costs. An interested party in an Aarhus Convention claim may therefore be entitled to a proportion of its costs, in circumstances where permission to seek judicial or statutory review is refused.

In coming to this conclusion, the Court of Appeal concluded that the absence of any express reference in CPR 45 to interested parties is “of no consequence”. The limits address the total costs exposure of the claimant and are not prescriptive as to the party to whom the claimant may be required to pay those costs. An interested party may therefore be entitled to its reasonable and proportionate costs, subject to the total costs cap in conjunction with the defendant and any other interested parties. See Campaign to Protect Rural England - Kent Branch v Secretary of State for Communities and Local Government[2019] EWCA Civ 1230.

Can interested parties apply to increase the cap?

Up until recently, this question was unresolved. Whilst CPR 45 expressly provides that a defendant can apply to vary the cap, it is again silent on the position of interested parties. However, earlier this month this question came before the High Court, following a decision refusing permission to proceed with a review on the papers, and a costs order extending the standard £5,000 cap. As the interested party had applied for a higher costs cap than that requested by the defendant, and the collective costs of the interested party and defendant exceeded the cap requested by the defendant, the question faced by the court was whether an interested party has standing to apply to vary the standard Aarhus Convention claim costs cap.

Following the Court of Appeal decision referred to above, the High Court concluded there was no doubt an interested party will be subject to the cost cap. Having done so, the court went on to find that it would be unjust (and contrary to principle) if the interested party then had no standing to ask the court to vary that cap. The fact that there were no express provisions in CPR 45 providing the right for an interested party to apply to vary the cap was of no consequence. See R (Bertoncini) v Hammersmith and Fulham LBC [2020] 6 WLUK 174.


It is encouraging to see the High Court recognise the value of interested parties’ engagement in environmental cases and the need to ensure that participation is not disincentivised by overly restricting costs recovery. This decision not only reiterates interested parties’ entitlement to costs, but also acknowledges that interested parties should have a voice on the standard costs caps to the extent they can expect to benefit.

Interested parties’ right to seek to vary the costs caps will continue to be balanced against the court’s obligation to satisfy itself that any variation should not make the proceedings prohibitively expensive for the claimant. Recovery caps will therefore continue to remain low compared with claims falling outside of the Aarhus Convention. As a result, the judgment is unlikely to bring about an immediate flood of interested parties becoming involved in environmental claims. However, the potential for additional costs protection will give some would-be interested parties a greater incentive to engage in claims, and would-be claimants may well see the decision as presenting an additional risk to bringing Aarhus Convention claims going forward.

As we continue to see an uptick in environmental and climate change-related judicial review, and as both public and economic interest in a green recovery abounds, there is certainly scope for interested parties to play a greater role in contributing new perspectives to the debate. The clarity this recent judgment provides on the costs position in Aarhus Convention claims is therefore a welcome one.