The law assuming reliability of computer evidence – and under which sub-postmasters were prosecuted by the Post Office – must be reviewed to avoid future miscarriages of justice, according to the professional body for IT.
BCS, The Chartered Institute for IT is calling for an end to the legal presumption that computer systems data are always correct, with no burden on the prosecution to prove it.
From 2000, the Post Office brought charges against over 700 staff, based on data from its flawed Horizon IT system. Some went to prison following convictions for theft, false accounting and fraud.
Presumption that computer is always right
Dr Sam De Silva, Chair of BCS’ Law Specialist Group and Technology Partner at international law firm CMS said: “The Post Office scandal highlights the dangers of unquestioningly accepting the output of IT systems as reliable evidence.
“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 prove that the outputs and logs from the computer system were flawed or not accurate. Yet how could non-IT specialists be expected to prove this when even some experienced IT professionals would find it a challenge to do so?
“If the Post Office had been required to prove that its computer system was operating reliably most of the individual cases against the Post office staff may well have had a different outcome.
“Organisations relying on evidence generated from computer systems to support prosecutions should be required to prove that the underlying computer system is reliable; we hope this will be a clear recommendation from the current inquiry.
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“Whilst the Post Office Scandal is the most high-profile case where the law in relation to the presumption of computer-generated evidence had inadvertent consequences, there have also been other cases in the past with similar issues.
“For example, there was a case involving a hospital in 2014 (R v Cahill; R v Pugh) involving an allegation that nurses falsified patient records because of discrepancies found with computer records. The presumption of computer-generated evidence led to a criminal trial.
“However, this trial was abandoned when the cause of the discrepancies was shown to be a problem with the IT database.”
