In the matter of an application by the Secretary of State for Northern Ireland for Judicial Review [2025] UKSC 47. Judgment 17 December 2025 here
More than 20 years ago 25-year-old Liam Thompson was shot and killed near a gap in a peace line separating nationalist and unionist neighbourhoods in Belfast. No one has ever been held accountable for his murder. Indeed, in the context of what the Supreme Court describe as “egregious and profoundly disturbing delays” there has still not been an effective and Article 2 compliant investigation into Mr Thompson’s death.
The abortive inquest that was commenced in 2023 has, however, given the Supreme Court cause to answer an important question of principle: What test, and what level of scrutiny, should be applied by a court reviewing a decision to disclose material over which a claim of Public Interest Immunity (‘PII’) has been made?
In a unanimous judgment, overturning the decisions of the Coroner, a High Court Judge, and two Court of Appeal judges, the Supreme Court affirms that the question whether evidence is covered by PII is a substantive question of the law of evidence, not an exercise of judicial discretion. A first instance court must determine where the overall public interest lies, by conducting the balancing exercise set out in R v Chief Constable of West Midlands Police, Ex p Wiley [1995] 1 AC 274. The inquisitorial nature of an inquest will raise the stakes in PII cases as compared to civil litigation. If the first instance court misidentifies the public interest, it has gone wrong in law and an appellate or reviewing court is required to consider the balancing exercise itself and correct the error.
The Inquest
The inquest into Mr Thompson’s death was opened in August 1995, it is not explained in this judgment why the actual inquest hearings did not begin until 3 April 2023. What we do learn is that despite the “valiant efforts” of the Coroner, there was yet further delay, with the third and final module of evidence, concerning how Mr Thompson came to his death, being listed to commence on 26 February 2024 and conclude by 8 March 2024, safely before the 1 May 2024 deadline that would guillotine all ‘Troubles inquests’ as consequence of s44(1) the Northern Ireland Troubles (Legacy and Reconciliation) Act 2023.[1]
However, module 3 never finished; the Coroner would eventually conclude that there could not have been viable inquest on the evidence available. This was because of a claim for PII, made on behalf of the Secretary of State for Northern Ireland (‘the Secretary of State’) and initially supported by the Chief Constable of the Police Service of Northern Ireland (‘the Chief Constable’), over 7 folders of documents relevant to the question whether security forces had received sensitive and secret information, or information from a covert human intelligence source, in relation to the deceased.
The PII claims in the inquest, High Court, and Court of Appeal
Before module 3 began, two PII certificates were issued on behalf of the Secretary in relation to folders 1-7, asserting that disclosure would be contrary to the public interest in protecting national security, as contrary to the policy of neither confirming nor denying the use of informers or other secret sources of information.
The Coroner upheld the PII claims but decided that the information in folder 7 should be gisted, and this gist (‘gist 1’) disclosed and admitted as evidence.
Gist 1 was objected to by both the Secretary of State and the Chief Constable, both of whom brought judicial review proceedings (heard by Mr Justice Humphreys) against the Coroner.
Following a suggestion from the Chief Constable, the Coroner proposed in a hearing before Humphreys J that she was minded to adopt and disclose a second gist (‘gist 2’). The Secretary of State amended his judicial review application to also challenge the decision in respect of gist 2; this challenge was stayed pending the resolution of the challenge regarding gist 1.
On 24 March 2024, Humphreys J delivered an open judgment dismissing the Chief Constable’s and Secretary of State’s challenges to the decision to disclose gist 1: [2024] NIKB 18. The Chief Constable thereafter dropped his challenge to gist 1.
The gist 2 challenge came alive after closed judgment in the gist 1 on 28 March 2024. The Secretary of State maintained his challenge to gist 2 and appealed against the disclosure of gist 1.
Between 22 March 2024 and 11 April 2024, the Coroner did not hold any hearing to consider submissions from the Secretary of State as to whether to disclose gist 2. On 11 April 2024, the Coroner delivered open and closed rulings deciding to disclose gist 2 rather than gist 1.
On 25 April 2024, Humphreys J dismissed the Secretary of State’s challenge to the Coroner’s decision to disclose gist 2: [2024] NIKB 32. A closed judgment was also delivered.
The Secretary of State appealed to the Court of Appeal against the orders of Humphreys J in relation to both gists. The Coroner undertook not to disclose either gist pending determination of the appeal.
The appeal was dismissed by a majority on 30 April 2024 see [2024] NICA 39 . Keegan LCJ giving an ex tempore judgment which Horner LJ agreed; McCloskey LJ dissented. The majority open judgments, and an open and closed written dissenting judgment, were delivered by the end of May 2025.
The Coroner gave an oral judgment, contemporaneous with the Court of Appeal’s ex tempore decision, that it was not possible to have a viable inquest as the 1 May 2024 deadline had not been met and because of her decision to uphold the PII certificates. She recommended a public inquiry be held.
Appeal to the Supreme Court
The question on appeal to the Supreme Court was whether a court reviewing a decision about the application of the PII to evidence is restricted to reviewing the decision on ordinary public law grounds, or whether an enhanced standard of review is required.
The Supreme Court on the Relevant PII Principles
The Supreme Court drew significantly on the case R v Chief Constable of West Midlands Police, Ex p Wiley [1995] 1 AC 274 (among others) in reaching its decision and in setting out the principles summarised below.
PII principles are concerned with determining whether evidence, otherwise relevant and admissible to proceedings, should be treated as inadmissible because of the prejudice disclosure would cause to some important aspect of the public interest. There is a single “public interest”, albeit comprised of various aspects; these aspects must be balanced to determine the public interest when considering a PII claim.
For example, national security is an aspect of the public interest commonly cited in support of a PII claim and cited in this case; the proper administration of justice is another aspect of the public interest, commonly weighed against national security when considering PII.
In identifying whether the asserted aspect of public interest is in issue, the courts will expect to be provided with evidence from an appropriate public authority, to which the courts, for reasons “constitutional … and … to do with relative institutional competence” afford a significant degree of respect [29].
Unless the assessment of the risk to the relevant aspect of public interest by the authority asserting PII is (i) irrational,(ii) unsupported by evidence, or (iii) defective for failure to take relevant matters into account, the court will accept that authority’s assessment of the risk posed to the public interest [35].
If multiple public authorities form different assessments of the risk to an aspect of the public interest, the first step should be consultation between the public authorities with a relevant interest in the matter with a view to trying to reach a consensus. It is inappropriate for the public authorities to proceed immediately to court to lay their differences before it to ask the court to determine the issue [60]. If no consensus is possible, the proper approach is for the public authority with the primary responsibly for the relevant interest to make the assessment and inform the court. In national security PII cases, this will typically be the Secretary of State (as it was in this case) [61].
If an aspect of the public interest points away from disclosure, the court must balance this against the aspect of public interest concerned with due administration of justice and should consider whether partial disclosure could be given (e.g., a gist). The court, not the authority asserting PII, is responsible for making this judgment [29].
Where a proper assessment of the public interest leads to the conclusion that the evidence should not be admitted, there is no discretion for the court: it is “a matter of obligation arising from the general law that the evidence must be excluded” [34].
As such, ordinary public law grounds applicable to reviewing the exercise of a discretion – considering whether the decision was unlawful, Wednesbury irrational, or tainted by material procedural unfairness – are not the appropriate standards of review. Rather, the appellate or reviewing court (as the case may be) must determine whether the first instance court has identified the relevant rule of substantive law and applied it correctly [124].
Further, the questions in the balancing exercise – whether the public interest requires that the [evidence] shall not be produced, and whether that public interest is so strong as to override the ordinary right and interest of a litigant that he shall be able to lay before a court of justice all relevant evidence – are questions which an appellate or reviewing court is as well placed as a first instance court to assess, and are questions of such intrinsic importance that it is appropriate for the appellate or reviewing court to form its own view as to the answers [125-128].
Decision on the Facts
Applying these principles, the Supreme Court identified six errors in the Coroner’s decisions to disclose the gists:
(a) the Coroner should have considered whether the Secretary of State’s assessment of the risk to national security was Wednesbury irrational rather than having “proper regard” to it [138];
(b) the Coroner wrongly concluded that she did not need to carry out a balancing exercise having gisted the material [140];
(c) when carrying out the balancing exercise in the alternative, the Coroner wrongly failed to weigh the Secretary of State’s assessment [142];
(d) the Coroner should have obtained the Secretary of State’s view before making any decision about disclosing the gists [144];
(e) the Coroner should have identified the Secretary of State as the PII applicant, not the Chief Constable [146]; and
(f) the Coroner failed to take into account in the balancing exercise the material consideration that there was no prospect of completing the evidence by 1 May 2024 [148].
The High Court and the majority of the Court of Appeal erred by failing to recognise these errors [139] [141] [143] [145] [147] [149], by concluding they were restricted to reviewing the Coroner’s decision on ordinary public law grounds rather than forming their own conclusion on the balancing exercise, and in various other respects [150-159].
The Supreme Court allowed the appeal on the facts: the balancing exercise showed that the balance of the public interest clearly lies against disclosure of the gists [164-5]. Of particular relevance was the statutory deadline meaning the inquest could not be completed and the impossibility of the Coroner fulfilling her functions given the PII decisions relating to files 1-7. A full investigation into Mr Thomspon’s death could be achieved by a statutory inquiry employing a special closed procedure or through a review undertaken by the Independent Commission for Reconciliation and Information Recovery [166].
Commentary
The Coroner, Ms Fee, need not feel too bad about the six errors the Supreme Court identified; after all, a High Court judge and two Court of Appeal judges had agreed with her approach.
As noted in the judgment, the inquisitorial nature of an inquest raises the stakes in PII cases as compared to civil litigation. Whereas a litigant in civil proceedings concerned about the detrimental impact on the public interest can make concessions or chose not to adduce evidence to avoid this impact, in an inquest there is no such option. Relevant material must be provided to the coroner, and it is the coroner who decides whether or not it is disclosed. The profound responsibility of identifying the overall public interest therefore weighs particularly heavily on coroners.
The applicable principles for the PII balancing exercise in an inquest were set out by Goldring LJ in Secretary of State for Foreign and Commonwealth Affairs v Assistant Deputy Coroner for Inner North London [2013] EWHC 3724 (Admin); [2013] Inquest LR 257 §§53-61 (the ‘Litvinenko’ case).
However, the Supreme Court cautioned coroners not to be misled by the fifth Litvinenko principle [130]: the relevant question when considering the asserted risk to e.g. national security by a PII applicant is not whether there are “cogent or solid” reasons to reject the assessment, but whether the assessment stands up to ordinary public law principles (i.e. is it rational, Wednesbury reasonable, have the relevant considerations been taken into account).
Coroners are also likely to be particularly assisted on the guidance as to the approach to be taken when public authorities disagree about the risk posed to national security (or other relevant aspect of the public interest). A coroner should take their cue from the authority with the primary responsibility for the relevant interest. As identified, in national security cases this is likely to be the Secretary of State.
Ian Skelt KC of Serjeants’ Inn chambers acted for the Coroner throughout this case
[1] See s16 of the Coroners Act (Northern Ireland) 1959 as amended by s44(1) of the Northern Ireland Troubles (Legacy and Reconciliation) Act 2023.