[SystemSafety] Post Office Horizon System

Peter Bishop pgb at adelard.com
Fri Jan 1 13:43:20 CET 2021


Yes the Post Office case was a scandal.
I was one of several contributors who assisted Stephen Mason (one of the
barristers in this trial)

The PO used some very dodgy statistical arguments to support their
reliability claim
- rebutted in:

https://ials.blogs.sas.ac.uk/2019/06/26/the-use-of-statistics-and-software-code/

And the PO also claimed that the Horizon system was robust, which was
challenged in:

https://ials.blogs.sas.ac.uk/2019/06/25/the-use-of-the-word-robust-to-describe-software-code/

Peter

On 16/12/2020 16:26, Peter Bernard Ladkin wrote:
> A couple of decades ago, the Post Office introduced a new WAN'd POS
> called Horizon. Various of its franchisees in the early years were
> accused of fraud; many were prosecuted and convicted; some were unable
> to offer any plausible defence except to say "I didn't do it; really I
> didn't; there must be some mistake".
>
> A class action Bates et al v Post Office was heard in 2019 before Mr.
> Justice Fraser. Fraser J conducted a superb judicial-forensic
> investigation from the bench, which determined more or less that the
> Horizon system was in fact itself capable of much of the erroneous
> behaviour which had been attributed to franchisee malfeasance in many,
> possibly even most, of the criminal cases which had been prosecuted.
> Subsequent to Fraser J's ruling, the Criminal Cases Review Commission
> determined quickly that many of the convictions were unsafe.
>
> Some of the problem lies in how UK law treats "electronic"/digital
> evidence, which includes evidence about the behaviour of digital
> systems. There is a history to this. Barrister Paul Marshall recently
> approached the Ministry of Justice about it. A paper with
> recommendations on how the law should approach this kind of evidence
> in the future was submitted on request to the Ministry in November
> 2020 and a slightly modified version has been published in an open
> access journal (indirect link below).
>
> Some of us on this list have been involved. I must say I am proud to
> have been able to help. I am sure my colleagues feel the same way. Pro
> bono publico. There is nothing more rewarding.
>
> https://ials.blogs.sas.ac.uk/2020/12/16/recommendations-for-the-probity-of-computer-evidence-requested-by-the-ministry-of-justice-now-published/
>
>
> PBL
>
> Prof. Peter Bernard Ladkin, Bielefeld, Germany
> ClaireTheWhiteRabbit RIP
> Tel+msg +49 (0)521 880 7319  www.rvs-bi.de
>
>
>
>
>
>
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-- 

Peter Bishop
Chief Scientist
Adelard LLP
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