Post Office Horizon Enquiry – Fujitsu Report on Eposs PinICL Task Force (1998)

Context: in the UK, the Post Office (rough equivalent of USPS) has local branches called Sub Post Offices that are run by local shopkeepers. In 1999 the Post Office rolled out a new system called Horizon, built by Fujitsu. It was badly built with several bugs in edge cases that would lead to incorrect accounting. Over the years this led to 700 subpostmasters (the local shopkeepers) being wrongly convicted of theft, fraud or false accounting. This destroyed many lives.

This scandal has been bubbling along for some decades but it broke into the mainstream this month when a major drama series about it was broadcast in the UK - Mr Bates vs The Post Office.

Linked document is an internal Fujitsu review of the code/bug fixing process from 1998. See page 17 onwards for some hair raising code examples.

    Public Function ReverseSign(d)
    If d < 0 Then
          d = Abs(d)
        Else
          d = d - (d * 2)
        End If
    ReverseSign = d
    End Function