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Post Office computer system legal case reaches important procedural juncture

Sub-postmasters group action against the Post Office reaches an important milestone

Legal teams representing sub-postmasters and the Post Office in a legal dispute over allegations that a faulty IT system caused account shortfalls are meeting with a High Court judge today (19 October) to set out a case timetable.

This is an important point in a group action brought against the Post Office by more than 500 sub-postmasters, after it was approved by the High Court earlier this year. In the litigation sub-postmasters claim they have suffered as a result of a faulty Post Office accounting system.

This follows years of dispute. In 2009, Computer Weekly revealed the plight of some sub-postmasters who had received heavy fines and even jail terms for alleged false accounting, which they blamed on the Horizon operating system and supporting processes. The Post Office has vehemently denied this claim (see timeline below).

Today’s hearing will see the legal teams on both sides of the dispute meet with the managing judge to set a case timetable.

It will be decided, at the hearing, whether and how expert evidence, including computer/IT evidence, can be used as part of the case. Experts have been vocal in regards to the Horizon system following sub-postmaster allegations that losses could be down to faults in the system.

Computer evidence key in sub-postmaster case

Computer evidence is core to the case. In November 2015, Computer Weekly revealed that technicians supporting the Post Office’s Horizon IT system admitted there was a known software flaw that could lead to sub-postmasters submitting inaccurate accounts. Post Office IT support sent an email to a member of the postmasters’ branch of the Communications Workers Union (CWU) which revealed the flaw.

The Post Office also appointed, and paid for, forensic investigation firm Second Sight to investigate the alleged problems with Horizon raised by sub-postmasters. But after Second Sight’s 96-page report was published in April 2015, saying that the Post Office had been too quick to take legal action against sub-postmasters, the Post Office published an 83-page report of its own claiming that Second Sight’s claims were wrong.

The Second Sight report said: “As a result of our investigations, we have established that the Post Office’s investigators have, in many cases, failed to identify the underlying root cause of shortfalls prior to the initiation of civil recovery action or criminal proceedings. This includes cases where applicants brought to the auditors’ or investigators’ attention their own suspicions as to the underlying root causes of their branches’ losses.”

Post Office IT system under scrutiny

In 2015, Andy Clark, visiting professor in information security at Royal Holloway University of London and director at information security and expert witness company Primary Key Associates, told Computer Weekly that over 10 years ago he was called as a witness for the defence in a case brought by the Post Office against a sub-postmaster. After seeing the Post Office Horizon accounting system in action, he said it was quickly apparent there were questions to ask about its integrity. After asking the Post Office these questions, the Post Office dropped the case, he said.

The Criminal Courts Review Commission (CCRC) is also looking at claims of wrongful prosecution of sub-postmasters. It has appointed a firm of forensic accountants to look into the Horizon IT system as part of its investigations.

Today’s High Court hearing will also decide whether extra time will be allowed to enable more sub-postmasters to be added to the action, what evidence will be produced by the parties, and when and whether test cases should be heard.

Post Office Horizon: Timeline of events

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