4 ms·

Post Office Horizon scandal explained: Everything you need to know

69 points by chrisjj 2y ago

manarth 2y ago
https://archive.is/TlCSu https://archive.is/TlCSu
velcrovan 2y ago
Lately loving this update of the old IBM slide [1]: A computer can never FIND OUT, so a computer must never FUCK AROUND. https://samim.io/p/2022-01-24-a-computer-can-never-be-held-accountable-an-ibm-slid/ https://samim.io/p/2022-01-24-a-computer-can-never-be-held-a...
- tantalor 2y ago
  Yeah that's what I don't get about this from the start. Accounting software is not a source of truth. It reflects reality. If there is a discrepancy, then you audit the accounts by comparing to reality, e.g. paper sales receipts.
  - tgaj 2y ago
    Do they even have paper sales receipts? Maybe the cash register is integrated with accounting software and is only printing receipts for customers.
    - throwaway173738 2y ago
      Someone involved in this project probably lost their voice chanting “paperless office” for a decade.
    - thwarted 2y ago
      Sales receipts are not necessarily a spool of paper. It's just a separate log of individual activity/events and is the source of truth for the list of transactions. A spool of paper is easy to make/inherently tamper-evident (for the risk profile of a cash register), but cryptographically signed/sealed logs that are sent (spooled!) to a parallel system in tandem also qualifies. If the "accounting software" is taking a shortcut by not recording an independent transaction log, the entire system is not very auditable.
  - chrisjj 2y ago
    Unfortunately Horizon replaced paper receipts.
  - surfingdino 2y ago
    And when you do, you might discover that your OCR system lies to you https://www.dkriesel.com/en/blog/2013/0802_xerox-workcentres_are_switching_written_numbers_when_scanning https://www.dkriesel.com/en/blog/2013/0802_xerox-workcentres...
- marcosdumay 2y ago
  > Have things changed since? Yes, things have changed. Managers now are also not held accountable.
loa_in_ 2y ago
Still most of the facts remain obscured. At least the sweep under the rug bandwagon has been outed.
tantalor 2y ago
Was there a root cause ever published?
- mike_hearn 2y ago
  That's what the inquiry is meant to do. British inquiries take forever and rarely yield any kind of justice, however. tl;dr summary is that the root cause depends on your perspective. If you have a CS background you might define the root cause as being the bugs. If you have a management background, you might conclude the root cause was bad/malign management by the board, the civil service and the C-suite. If you have a legal background you might conclude the root cause was the unusual prosecutorial powers, the default assumption courts make that computers aren't wrong and so on. As this is Hacker News let's roll with the first. There were many different bugs over many years and there was no single root cause. For example at least one case was caused by defective touch screen hardware that would go haywire when nobody was around to see it e.g. overnight, and start generating random clicks. Given enough random button pushes it was possible to ring up transactions that never happened, and thus never had money deposited in the till, creating phantom losses. In other cases there was loss of transactional integrity. Database writes went missing or got duplicated due to race conditions, not helped by the original Horizon architecture in which the connection to the central DB was asynchronous, due to the existence of post offices in very rural places without good internet connectivity. It's what would nowadays be called a "local-first distributed edge deployment" or something similar. Lots of ways for that to go wrong, and if you don't have exactly-once execution in an accounting system it will appear that cash was stolen because the records say a sale or refund was made, but it wasn't.
  - janice1999 2y ago
    > summary is that the root cause depends on your perspective. This sounds like an exercise in obfuscating responsibility. Post Office management knew from 2003 Horizon was unreliable - they chose to bury the report. They lied in court about its reliability and manipulated expert statements to say the same. They also knowingly lied about remote altering of accounts and buried a report in 2017 on it. Let's not get lost in the weeds - the root cause of the injustice is Post Office management.
egberts1 2y ago
The best way for subpostmaster to defend themselves in court is to get the Horizon to prove itself through double-column, and recouncilation of their own general ledger. Unable to do that? Horizon eats it.
- ndsipa_pomu 2y ago
  Unfortunately, in England and Wales, courts consider computers, as a matter of law, to have been working correctly unless there is evidence to the contrary. Therefore, evidence produced by computers is treated as reliable unless other evidence suggests otherwise. This way of handling evidence is known as a ‘rebuttable presumption’. A court will treat a computer as if it is working perfectly unless someone can show why that is not the case. (taken from https://www.benthamsgaze.org/2022/06/30/the-legal-rule-that-computers-are-presumed-to-be-operating-correctly-unforeseen-and-unjust-consequences/ https://www.benthamsgaze.org/2022/06/30/the-legal-rule-that-...) The sub post masters did not have access to the evidence required to show that the Horizon system was buggy and so were denied justice.
  - jabroni_salad 2y ago
    per the submitted post, it seems that every time a sub postmaster manages to get an expert witness into court, the PO ends up settling out of court instead of continuing legal actions. For really good and pure reasons I am sure.
    - ndsipa_pomu 2y ago
      Quite. The higher ups at the Post Office clearly knew about the bugs in the system and took steps to avoid any public disclosure of them.
    - qingcharles 2y ago
      This is why expert defense witnesses are important, but usually only the prosecution (government) has the budget for an expert, or a competent expert. In the USA the courts are supposed to provide an expert for the defense upon request, but this rarely happens, or when it does, the budget is so small that nobody competent can be found.
ndsipa_pomu 2y ago
It's a disgrace that no-one has been prosecuted for this travesty of justice. I don't understand how they were able to rely on falsehoods to get convictions and then not be prosecuted for perjury and conspiracy to pervert the course of justice. There's also the issue of the Post Office "recovering" money from sub post masters that wasn't actually missing - that is surely fraud. There needs to be some lengthy jail terms for the higher-ups responsible for overseeing this.
- qingcharles 2y ago
  In the whole of history I only know of one prosecutor who was criminally charged for a wrongful conviction. And they weren't the one that did it. They just took a deathbed confession from their colleague and failed to report it.
toomuchtodo 2y ago
https://en.wikipedia.org/wiki/British_Post_Office_scandal https://en.wikipedia.org/wiki/British_Post_Office_scandal
deleted 2y ago
[deleted]
PM_me_your_math 2y ago
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69 points by chrisjj 2y ago

https://archive.is/TlCSu https://archive.is/TlCSu

Lately loving this update of the old IBM slide [1]: A computer can never FIND OUT, so a computer must never FUCK AROUND. https://samim.io/p/2022-01-24-a-computer-can-never-be-held-accountable-an-ibm-slid/ https://samim.io/p/2022-01-24-a-computer-can-never-be-held-a...

tantalor 2y ago
Yeah that's what I don't get about this from the start. Accounting software is not a source of truth. It reflects reality. If there is a discrepancy, then you audit the accounts by comparing to reality, e.g. paper sales receipts.
- tgaj 2y ago
  Do they even have paper sales receipts? Maybe the cash register is integrated with accounting software and is only printing receipts for customers.
  - throwaway173738 2y ago
    Someone involved in this project probably lost their voice chanting “paperless office” for a decade.
  - thwarted 2y ago
    Sales receipts are not necessarily a spool of paper. It's just a separate log of individual activity/events and is the source of truth for the list of transactions. A spool of paper is easy to make/inherently tamper-evident (for the risk profile of a cash register), but cryptographically signed/sealed logs that are sent (spooled!) to a parallel system in tandem also qualifies. If the "accounting software" is taking a shortcut by not recording an independent transaction log, the entire system is not very auditable.
- chrisjj 2y ago
  Unfortunately Horizon replaced paper receipts.
- surfingdino 2y ago
  And when you do, you might discover that your OCR system lies to you https://www.dkriesel.com/en/blog/2013/0802_xerox-workcentres_are_switching_written_numbers_when_scanning https://www.dkriesel.com/en/blog/2013/0802_xerox-workcentres...
marcosdumay 2y ago
> Have things changed since? Yes, things have changed. Managers now are also not held accountable.

loa_in_ 2y ago

Still most of the facts remain obscured. At least the sweep under the rug bandwagon has been outed.

tantalor 2y ago

Was there a root cause ever published?

mike_hearn 2y ago
That's what the inquiry is meant to do. British inquiries take forever and rarely yield any kind of justice, however. tl;dr summary is that the root cause depends on your perspective. If you have a CS background you might define the root cause as being the bugs. If you have a management background, you might conclude the root cause was bad/malign management by the board, the civil service and the C-suite. If you have a legal background you might conclude the root cause was the unusual prosecutorial powers, the default assumption courts make that computers aren't wrong and so on. As this is Hacker News let's roll with the first. There were many different bugs over many years and there was no single root cause. For example at least one case was caused by defective touch screen hardware that would go haywire when nobody was around to see it e.g. overnight, and start generating random clicks. Given enough random button pushes it was possible to ring up transactions that never happened, and thus never had money deposited in the till, creating phantom losses. In other cases there was loss of transactional integrity. Database writes went missing or got duplicated due to race conditions, not helped by the original Horizon architecture in which the connection to the central DB was asynchronous, due to the existence of post offices in very rural places without good internet connectivity. It's what would nowadays be called a "local-first distributed edge deployment" or something similar. Lots of ways for that to go wrong, and if you don't have exactly-once execution in an accounting system it will appear that cash was stolen because the records say a sale or refund was made, but it wasn't.
- janice1999 2y ago
  > summary is that the root cause depends on your perspective. This sounds like an exercise in obfuscating responsibility. Post Office management knew from 2003 Horizon was unreliable - they chose to bury the report. They lied in court about its reliability and manipulated expert statements to say the same. They also knowingly lied about remote altering of accounts and buried a report in 2017 on it. Let's not get lost in the weeds - the root cause of the injustice is Post Office management.

egberts1 2y ago

The best way for subpostmaster to defend themselves in court is to get the Horizon to prove itself through double-column, and recouncilation of their own general ledger. Unable to do that? Horizon eats it.

ndsipa_pomu 2y ago
Unfortunately, in England and Wales, courts consider computers, as a matter of law, to have been working correctly unless there is evidence to the contrary. Therefore, evidence produced by computers is treated as reliable unless other evidence suggests otherwise. This way of handling evidence is known as a ‘rebuttable presumption’. A court will treat a computer as if it is working perfectly unless someone can show why that is not the case. (taken from https://www.benthamsgaze.org/2022/06/30/the-legal-rule-that-computers-are-presumed-to-be-operating-correctly-unforeseen-and-unjust-consequences/ https://www.benthamsgaze.org/2022/06/30/the-legal-rule-that-...) The sub post masters did not have access to the evidence required to show that the Horizon system was buggy and so were denied justice.
- jabroni_salad 2y ago
  per the submitted post, it seems that every time a sub postmaster manages to get an expert witness into court, the PO ends up settling out of court instead of continuing legal actions. For really good and pure reasons I am sure.
  - ndsipa_pomu 2y ago
    Quite. The higher ups at the Post Office clearly knew about the bugs in the system and took steps to avoid any public disclosure of them.
  - qingcharles 2y ago
    This is why expert defense witnesses are important, but usually only the prosecution (government) has the budget for an expert, or a competent expert. In the USA the courts are supposed to provide an expert for the defense upon request, but this rarely happens, or when it does, the budget is so small that nobody competent can be found.

ndsipa_pomu 2y ago

It's a disgrace that no-one has been prosecuted for this travesty of justice. I don't understand how they were able to rely on falsehoods to get convictions and then not be prosecuted for perjury and conspiracy to pervert the course of justice. There's also the issue of the Post Office "recovering" money from sub post masters that wasn't actually missing - that is surely fraud. There needs to be some lengthy jail terms for the higher-ups responsible for overseeing this.

qingcharles 2y ago
In the whole of history I only know of one prosecutor who was criminally charged for a wrongful conviction. And they weren't the one that did it. They just took a deathbed confession from their colleague and failed to report it.

toomuchtodo 2y ago

https://en.wikipedia.org/wiki/British_Post_Office_scandal https://en.wikipedia.org/wiki/British_Post_Office_scandal

deleted 2y ago

[deleted]

PM_me_your_math 2y ago

[dead]