The professional body for IT in Britain has called for a review of a law that assumes the reliability of computer evidence.

BCS, the Chartered Institute for IT, wants an end to the legal presumption that computer-systems data is always correct, with no burden on the prosecution to prove it.

The call comes in the wake of the Post Office Horizon scandal in the UK, which led to hundreds of postmasters being wrongly prosecuted or convicted for false accounting, theft, and fraud due to glitches in a software system that incorrectly showed money missing from accounts in post-office branches.

The British Government last week pledged to legislate to exonerate all victims through legislation.

Legal presumption

Dr Sam De Silva (chair of BCS’s Law Specialist Group and technology partner at 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,” he continued.

“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?” Dr De Silva asked.

He said that organisations relying on evidence generated from computer systems to support prosecutions should be required to prove that the underlying computer system is reliable.

Hospital case

The IT expert added that the Post Office case had not been the only one to raise similar issues, citing a case involving a hospital in 2014 in which nurses were alleged to have falsified patient records because of discrepancies found in computer records.

“The presumption of computer-generated evidence led to a criminal trial,” Dr De Silva said. “However, this trial was abandoned when the cause of the discrepancies was shown to be a problem with the IT database.”

According to the Law Society Gazette of England and Wales, courts have been required since 1999 to follow the common-law assumption that a computer producing the evidential record is working properly, and that the record is admissible.

Previously, section 69 of the Police and Criminal Evidence Act 1984 required anyone introducing computer-generated evidence to show the system was operating correctly, and not being used improperly.