Overview
A key task for prosecutors handling vast quantities of digital data is working out how to determine efficiently whether any given document meets the test for disclosure. Prosecutors such as the Serious Fraud Office (SFO) must determine whether material might reasonably be considered capable of undermining their case or assisting the case for the defence. A key role for the defence is to engage with the prosecution to meet their disclosure obligations, which can happen in two ways: firstly, by defining the real issues in the case; secondly, by defining the scope of searches made over the digital data to identify material.
It is in this context that search terms are necessary in narrowing the vast volume (often several millions) of documents. However, the software platforms used by the SFO in applying agreed search terms have shown to not always work as intended. The key risk of documents not being reviewed and disclosed is that the SFO is not releasing material when under a duty to do so and potential exculpatory evidence is withheld from the defence.
The SFO has established an internal working group, working alongside the Attorney General's Office and HM Crown Prosecution Service Inspectorate ("HMCPSI"), with the remit to review its cases that used the SFO's legacy document review platform, Autonomy. This working group is established to ascertain whether relevant and disclosable material exists which could cast doubt on the safety of any convictions. The SFO is also reviewing its current document review platform Axcelerate.
An initial update by the SFO's Interim Director of Legal Services, Matthew Wagstaff, published on 3 February 2025 notes that its current document review platform Axcelerate, as well as its previous platform Autonomy, have encountered separate issues that could impact upon its ability to meet its disclosure obligations. The SFO's position is that it has not seen any evidence that this is the case and that there are no unsafe convictions.
Background to the SFO's e-discovery review
Disclosure is a challenge for the SFO. Documents frequently number in the millions, have a large number of custodians, hundreds of devices must be searched, and everything must be forensically recorded. However, even though disclosure is a difficult exercise to get right, especially in complex fraud cases, it is not impossible and it is incumbent on a prosecutor to discharge their duties to the defence.
There have been two notable examples in recent years where the disclosure process led to two cases collapsing. In April 2021 the prosecution against two Serco employees collapsed, where the disclosure process resulted in relevant evidence being withheld from the defendants. In March 2023 the SFO offered no evidence against the three defendants in the G4S prosecution, because of repeated delays arising from disclosure issues.
A report from the HMCPSI in April 2024 suggested that the defence was partly to blame for the disclosure issues on the G4S case, because of a lack of engagement, which ignores the fact that the prosecution are in possession of all the evidence and have a much better understanding of both the issues in the case, as well as where documents that may assist the defence can be located. Of more importance are observations that Autonomy, the SFO's legacy document review platform, had technical limitations: "certain punctuation affected search terms and impacted on the resulting documents identified."
Difficulties surrounding Autonomy
If the SFO ran keyword searches over a pool of documents, it would not return documents if the keyword was immediately followed by a "tangible character" – for example punctuation marks. If the word "bribery" was searched, Autonomy would be unable to return documents that contained "bribery." ie the search term with a punctuation mark immediately following it. The April 2024 HMCPSI report states that the issue was discovered in "the second half of 2022" and that "The SFO's internal guidance did specify how search terms functioned on Autonomy and specifically how punctuation impacted upon those terms." The difficulty was compounded because Autonomy was unsupported, meaning that once issues were identified it was very difficult for these to be rectified.
Perhaps one of the principal concerns arising from Mr Wagstaff's initial report is that none of these issues are new. Having discovered the issue in 2022 it has taken an alarming amount of time to even receive confirmation that some cases using the legacy Autonomy system may have been affected. A report from HMCPSI in October 2019 into case progression in the SFO noted that "Every new [SFO] case since May 2018 has been uploaded on the new Axcelerate system." The report further noted that the Inspectorate could find no issues with either Autonomy or Axcelerate in recording digital material generated by SFO investigations and allowing effective review.
Evidently circumstances have changed since the October 2019 HMCPSI report with Axcelerate being the SFO's preferred platform since May 2018. However given the length of time SFO cases can take, there may be several cases in the pipeline that would have used Autonomy at some point in their lifecycle. Notably, Mr Justice Johnson in the G4S proceedings (which was heard in 2022) remarked that Autonomy's system of excluding results because of appending punctuation was a "flaw in the initial [disclosure] process."
The consequence for convicted defendants and current cases
The initial findings of the working group's report are that it has not yet discovered any evidence that might cast doubt on the security of any defendant's conviction. It is understood that the SFO have reached out to the legal teams of convicted defendants, suggesting that enquiries are ongoing and that it is taking these concerns seriously. However, it is disappointing that given the SFO was on notice about Autonomy issues since 2022 it is only reaching out to defence teams two years down the line. It is however encouraging that the working group is being overseen by an independent oversight group. Where the SFO has decided that a conviction is secure, it should share its methodology with the defence representatives and invite representations.
Given the long-term nature of much of the SFO's caseload, it is likely that there are several cases that had documents hosted on Autonomy before being migrated to Axcelerate. Historic search terms ought to be revisited to ensure no documents have fallen through the gaps. Defence teams ought to consider engagement with the SFO when it comes to the formulation of search terms, if in their clients' interests to do so.
Mr Wagstaff's update further notes that the SFO's work is ongoing and that another update on the issue is expected in the coming months. The SFO's confirmation that they are prioritising cases where defendants are serving custodial sentences is a welcome one. Any update should set out whether the representatives of convicted defendants are challenging those convictions, as well as the extent to which the issues are affecting current prosecutions.
In the interim, no doubt the legal teams of convicted defendants where disclosure issues arose are following this matter very closely. Irrespective of the SFO's position that it has full confidence in the safety of the convictions of all cases it has brought, it is possible that defence teams will take a different view and that appeals to the Court of Appeal and/or the Criminal Cases Review Commission may well be forthcoming pending final outcomes of the SFO's review.
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