The Justice Secretary has been urged to reconsider a law supported by the Post Office that assumes evidence derived from a computer is reliable. MPs and advocates for the sub-postmasters who were wrongfully convicted of financial crimes are calling on Alex Chalk to amend the law to prevent similar injustices in the future. The Post Office pushed for this rule in the 1990s, which led to the conviction of hundreds of sub-postmasters based on evidence from the Horizon computer system used in their branches. However, it was later discovered that this evidence was flawed due to software errors, resulting in account shortfalls for which sub-postmasters were wrongly blamed and some were even jailed. Nearly 100 people have had their convictions overturned so far, and the government is considering exonerating hundreds more.
The current legal rule states that courts should assume a computer system has operated correctly unless there is explicit evidence to the contrary. This replaced a previous law that required prosecutors to verify the proper functioning of a computer system when using evidence derived from it. The Post Office argued that these “technical requirements” hindered successful prosecutions, as revealed in documents submitted to the Law Commission in 1995.
‘Law is outdated’
Campaigners are advocating for a change in the legal rule, shifting the burden onto prosecutors like the Post Office to demonstrate the correct operation of any computer system if they intend to rely on evidence from it. Kevan Jones, the MP leading the campaign to clear the sub-postmasters, believes that the current rule is outdated and fails to consider software or coding issues. Barrister Stephen Mason, editor of Electronic Evidence, also supports a change in the law, arguing that the presumption that computer output is always accurate is absurd.
‘The truth is the precise opposite’
In August 2020, Justice Secretary Alex Chalk commissioned a paper on improving the approach to proving computer-derived evidence in court proceedings. The paper, written by barrister Paul Marshall, recommended that prosecutors using electronic evidence should provide sufficient details of their systems to demonstrate professional management. However, in May 2022, the then justice minister James Cartlidge stated that the government had no plans to review the presumption, as it was rebuttable if there was evidence to the contrary. Officials argued that it was similar to presuming the accuracy of breathalyser results or forensic tests unless proven otherwise. The ongoing public inquiry into the Post Office scandal will advise the government on this matter.
Mr. Marshall criticized the government for being indifferent to the harm caused by the presumption and highlighted the fallacy that most computer errors are visible or caused by operator input. He emphasized that the massive civil litigation involving the Post Office demonstrated that the presumption is simply wrong.