The announcement that the use of computer evidence in court is to be reviewed by the Ministry of Justice (MOJ) after the Post Office Horizon scandal has been welcomed by BCS, The Chartered Institute for IT.
The criminal justice system presumes that computers work correctly and software-generated evidence is accurate unless there is evidence to the contrary. However, this was proved flawed by the wrongful convictions of hundreds of subpostmasters.
To prevent future miscarriages of justice, it is asking to hear views from experts “across the justice system and beyond” on how to treat computer evidence.
The call-out launched on 21 January 2025 will last for 12 weeks and is part of the Government’s attempt to restore public confidence in policing and the criminal justice system.
Justice minister Sarah Sackman KC said: “We must learn the lessons of the Post Office scandal. A blanket ‘no questions asked’ acceptance of the accuracy of digital evidence can have a devastating impact on people’s lives. We need to carefully consider how we can both use and interrogate digital evidence in court. Ensuring people are protected from miscarriages of justice is vital, and one part of the Government’s Plan for Change.”
Computer evidence is central to many prosecutions including for fraud, rape and serious sexual offences. Additional measures to prove computer devices work correctly could affect how fast cases are completed. Therefore, any reform must be well thought out and future proofed according to the MOJ.
The review is seeking expert input on how to define computer evidence and what could be included in changes to the law. General digital evidence like text messages or social media posts may need to be treated differently to “evidence which has been specifically generated by a computer system or software”.
The MoJ said: “The miscarriages of justice which occurred in the Post Office cases were down to deliberate failures to properly interrogate and disclose evidence – which prevented postmasters and others from effectively challenging the reliability of the Horizon computer system evidence. Any changes to the presumption would not be able to further protect against instances where parties mislead a court on the accuracy of the evidence.
But lying in court – or perjury – is a separate crime already. However, removing or changing this presumption could mean defendants are better equipped to interrogate computer evidence against them, and would put more onus on the party supplying the digital evidence to ensure it can stand up to scrutiny.”
More than 900 sub-postmasters were prosecuted between 1999 and 2015 after faulty Horizon accounting software made it look as though money was missing from their accounts.
For you
Be part of something bigger, join BCS, The Chartered Institute for IT.
The Law Society of England and Wales chief executive, Ian Jeffery, said: “It is important that the Government considers the relaxation of the rule of evidence, which created a presumption that evidence generated by computers is accurate and contributed to the miscarriages of justice in the Post Office scandal, and if it should be reformed.”
BCS, The Chartered Institute for IT, works to improve competence and conduct in the IT industry and has campaigned for change on computer evidence in court.
Dr Sam De Silva, Chair of the Law Specialist Group for BCS, The Chartered Institute for IT and a partner with law firm CMS said: “The Post Office scandal highlighted the dangers of unquestioningly accepting the output of IT systems as reliable evidence. Today, there remains a legal presumption that the computer is always right. The Post Office could rely on the common law position that the courts were entitled to assume that the IT system was operating correctly. Without the benefit of the advice of IT experts supporting them, it was for the Post Office staff to demonstrate that the outputs and logs from the computer system were inaccurate.”
Dr De Silva questioned how people who are not IT specialists could be expected to do so given IT professionals were likely to find it challenging.
“If the Post Office had been required to prove that its computer system was operating reliably it is highly likely that the majority of the individual cases against the Post Office staff may well have had a different outcome.”
