The Justice Secretary has been urged to scrap a law that was backed by the Post Office and requires courts to presume that evidence derived from a computer is reliable.
MPs and campaigners for the sub-postmasters wrongly convicted of financial crimes are calling on Alex Chalk to amend the law to prevent a repeat of their unjust experiences.
The Post Office advocated for this rule in the 1990s, before the scandal involving hundreds of sub-postmasters who were convicted of theft based on evidence from the Horizon computer system used in their branches.
Subsequently, it was discovered that this evidence was unreliable due to errors in the software, which led to account shortfalls and wrongful blame on the sub-postmasters.
Almost 100 people have had their convictions overturned, and the government is considering exonerating hundreds more.
The current legal rule assumes that 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 correct functioning of the system when using evidence derived from computers. The Post Office argued that these technical requirements hindered successful prosecutions.
‘Law is outdated’
Campaigners are advocating for a change in the law, shifting the burden onto prosecutors like the Post Office to demonstrate the correct operation of any computer system when relying on evidence from it.
Kevan Jones, the MP leading the campaign, believes that the current rule is outdated and fails to consider software or coding issues. He stated, “The law needs to be changed. I understand there have been calls for this from members of the judiciary who are aware the law is outdated. It is not just Horizon, it is similar with bank fraud cases.”
Barrister Stephen Mason, editor of Electronic Evidence, also supports a change in the law. He argues that the presumption that computer output is always true is absurd, as complex software contains many errors.
‘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, then justice minister James Cartlidge stated that the government had no plans to review the presumption, as it had a wide application and could be rebutted with evidence to the contrary.
Mr. Marshall accused the government of being indifferent to the damage caused by the presumption. He emphasized that most computer errors are not visible or apparent to an operator and that the presumption is fundamentally flawed.
