The High Court has considered the principles applicable to the admissibility of expert evidence in judicial review proceedings, as well as the weight to be given to witnesses’ comments that stray beyond opinion into argument (R (Gardner) v Secretary of State for Health and Social Care [2021] EWHC 2946 (Admin)).

Key points

  • In judicial review proceedings it is not the function of the Court to assess the merits of the decision under challenge. The issue is whether the decision was lawful, not whether it was ‘right’. Evidence not before the decision-maker, such as that of experts relating to the period after the decision was made, is seldom required to resolve that issue.
  • The admissibility of expert evidence will depend on what type of evidence it is. Whilst statements of fact may assist the Court in understanding the context of the decision in question, statements of expert opinion will only be admitted if they were available at the time of the decision, and those amounting to legal argument will generally be given little weight.
  • The Court will try to take a proportionate approach to inadmissible evidence at the interlocutory stage. Parties will not necessarily be required to re-file statements. Instead, the Court may invite them to make submissions at the substantive hearing as to the appropriate weight to be given to particular passages.


The Claimants, the children of two care home residents who died during the first wave of the coronavirus pandemic between March and June 2020, issued judicial review proceedings against three Government bodies challenging their alleged failure to protect care home residents in England over that period: the Secretary of State for Health of Social Care, NHS England, and Public Health England. It was claimed that the conduct of the Defendants breached both Articles 2 (right to life) and 8 (right to private and family life) of the European Convention on Human Rights (“ECHR“), as well as the domestic public law principle of rationality.

The Claimants filed two witness statements given by medical consultants, which contained opinions severely critical of the Defendants. At the interlocutory stage, the issue before the Court concerned the Claimants’ application to file a further, third statement and the Defendants’ cross-application to resist this and to excise a number of passages from the statements already filed. The substantive hearing in the case is scheduled to take place in March 2022.


The High Court (constituted as the Divisional Court) rejected the Claimants’ application to adduce the third statement, as it consisted entirely of criticisms of the Defendants’ evidence. However, the Court considered it disproportionate to have the Claimants’ other two statements re-filed; passages amounting to argument would instead be given little weight at the substantive hearing, whilst those expressing an opinion on the reasonableness or negligence of the Defendants’ conduct would be inadmissible.

In reaching this decision, the Court considered the principles applicable to expert evidence in judicial review, both in relation to ECHR claims and domestic law grounds of challenge. For these purposes, it did not consider it relevant that the expert evidence which the Claimants sought to rely upon was contained in witness statements, as opposed to expert reports.

The Court explained that whilst evidence of opinion from an expert is admissible with the permission of the Court in ordinary civil claims under Part 35 of the Civil Procedure Rules, the Court is less willing to provide that permission in judicial review proceedings. This difference in treatment was explained by reference to the Divisional Court’s decision in R (The Law Society) v The Lord Chancellor [2018] EWHC 2094 (Admin), which the Court described as “an authoritative review of the law” on this point. Given the function of judicial review is not to assess the merits of the decision being challenged, it is rarely appropriate for the Court to consider evidence going beyond that which was available to the decision-maker, such as that given by experts.

Applying these principles, the Court held that expert evidence of opinion was admissible to the extent that it was available at the time of the decisions in question. For example, a Guardian article written by one of the consultants stating that care home residents should be made to isolate, published in March 2020, was admissible. But a statement that the Government’s failure to do so was negligent, given by the same consultant as a witness in litigation a year later, was not. Expert evidence of fact, namely as to what had taken place in care homes over the first wave of the pandemic was, however, admissible.

The Claimants contended that, even if there were grounds for declining to admit expert opinion as a matter of domestic law, the position was different in relation to the ECHR claims. It was argued that Article 2 in particular mandated closer scrutiny of the facts than under a rationality challenge alone. The Court agreed to proceed on the basis of that assumption at this interlocutory stage of the proceedings. Accordingly, the Claimants were permitted to refer, not just to the material on which the Defendants based their decisions, but to all other material (including expert evidence of opinion) that they could reasonably have accessed. However, the Court held that this did not extend to opinion evidence post-dating the decisions being challenged – admitting such evidence “would become entirely unmanageable“.

Finally, the Court addressed the sections of the three witness statements that were neither opinion nor fact, but argument. These included comments by witnesses as to whether the Defendants’ actions were ‘appropriate’ or ‘proportionate’. In line with decision in R (The Good Law Project Ltd) v Minister for the Cabinet Office [2021] EWHC 2091, the Court held that it would not take an “excessively purist” approach, reviewing line-by-line to remove such comments. It would instead consider submissions from Counsel at the substantive hearing as to the weight to be given to them.


The guidance on the admissibility of expert evidence in judicial review provided in the case of R (Law Society) v The Lord Chancellor has again been affirmed as authoritative (see our previous e-Bulletin). Whilst expert evidence may be admitted, it is seldom required to resolve the issues in judicial review. This is because the Court’s role is not to determine the merits of the decision, but to assess its lawfulness. To answer that question, material not before the decision-maker, such as expert evidence, is generally not required. Whether it is required and should be admissible will depend on the kind of expert evidence it is – evidence of fact, of opinion, or of argument.

The Court’s decision also indicates that in relation to grounds of challenge brought under the ECHR, claimants may have a greater range of evidence admitted, given the closer scrutiny of the decision those grounds may require.

Andrew Lidbetter
Andrew Lidbetter
+44 20 7466 2066
Nusrat Zar
Nusrat Zar
+44 20 7466 2465
Jasveer Randhawa
Jasveer Randhawa
Of Counsel
+44 20 7466 2998
Kyle Johnson
Kyle Johnson
+44 20 7466 2684