The comments come as the Scottish Criminal Cases Review Commission (SCCRC) concluded six sub-postmasters caught up in the scandal may have been victims of miscarriages of justice.
The six, one of whom has since died and is represented posthumously, are now entitled to appeal against the convictions for crimes of dishonesty arising from their roles as sub-postmasters at Post Office Ltd. Five other cases are still being reviewed by the review commission.
This includes the case of Aleid Kloosterhuis, who pled guilty to embezzlement and was sentenced to 12 months in prison. The other cases include that of Susan Sinclair, Anne Quarm on behalf of William Quarm (deceased), Colin Smith, Judith Smith and Robert Thomson.
Scottish cases connected to this scandal are critically different in that the Crown Office acted as prosecutor, rather than the Post Office, which acted as a private prosecutor in England and Wales. The commission concluded the actions of the Post Office during its investigations could be attributed to the state, with the information about the Horizon system having a material bearing on critical evidence in the trial of Sinclair.
The other five cases, where each accused pled guilty, the commission concluded they did so in circumstances which were clearly prejudicial to them, with the evidence around Horizon essential in proving the alleged accounting shortfall.
The scandal is one of the biggest miscarriages of justice in British history. More than 700 sub-postmasters were falsely prosecuted between 2000 and 2014 based on information from the Post Office’s computerised accounting and sales system Horizon.
Dr Andrew Tickell, law lecturer at Glasgow Caledonian University, said the Crown Office would be facing considerations around whether the Post Office or individuals in the company had perverted the course of justice by asking prosecutors to rely on flawed evidence.
He said: "In England and Wales, the Post Office acted as a private prosecutor. In Scotland, they had to pass evidence to independent prosecutors to determine whether anyone should be prosecuted for crimes of dishonesty.
"Until this SCCRC referral, it was unclear how many – if any – Scottish sub-postmasters and mistresses had faced false accusations of theft, fraud or embezzlement based on the flawed Horizon accounting system. The Appeal Court will now consider whether these cases constitute miscarriages of justice.
"The Crown Office must be asking itself – did anyone at the Post Office attempt to pervert the course of justice by inducing public prosecutors to rely on this fundamentally flawed computer evidence?”
Michael Walker, the commission’s chief executive, said: “These cases posed significant challenges for the commission. Similar cases have been litigated in England and Wales, and lengthy decisions and voluminous papers exist in relation to those court actions. We were required to consider that information and to obtain materials relevant to the six cases that we are referring today.”
A Crown Office and Procurator Fiscal Service spokesman said: “We note the terms of the Scottish Criminal Cases Review Commission referral.”