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The fallibility of electronic evidence

‘The law needs to urgently move into the twenty-first century’ says author and barrister Stephen Mason

‘English justice is beyond satire’ Simon Jenkins wrote in a recent article for The Guardian describing, among other miscarriages of justice, the Post Office’s Horizon scandal, when more than 700 postal workers were prosecuted for theft, fraud and false accounting between 1999 and 2015 linked to a faulty IT system.

‘Just 132 had the energy and resources to appeal against their conviction, of whom 88 were successful. Dozens either lost heart or had their appeals thrown out. Only in 2021 did the court of appeal admit its decisions had been “an affront to the conscience of the court”. But the government, which owns the Post Office, allowed its executives to take home handsome bonuses, partly for working on the inquiry itself.’

The Guardian, 26th October 2023

Mr Bates Vs The Post Office, a new ITV drama, has stirred up public interest in the inquiry, and it’s been reported this week that Paula Vennells, former head of the Post Office, has handed back her CBE.

But for students and scholars of law who wish to understand the case more fully, it goes back to the common law presumption in the law of England and Wales, formulated by the Law Commission in 1997, that ‘In the absence of evidence to the contrary, the courts will presume that mechanical instruments were in order at the material time.’

Stephen Mason, a leading authority on electronic evidence and electronic signatures and editor of Electronic Evidence and Electronic Signatures published by University of London Press, had the following letter published in The Times yesterday:

Dear Editor,

In 1999 Parliament changed the law so that courts presume that evidence derived from a computer is reliable. The presumption effectively ‘magics’ computer output into truth. This presumption is absurd, of course, because all complex software contains many errors.

The burden of proof is reversed. Showing the contrary, as the Post Office Horizon scandal eloquently attests, can be a burden that a defendant to a criminal charge (or civil claim) will rarely be unable to discharge, because they have no direct knowledge of the computer system, with disastrous consequences.

To stand any chance of challenging computer evidence, a defendant must be given appropriate disclosure of relevant evidence of the system. It is a poor excuse to claim it is expensive to provide routine information relating to computer bugs. The fairness of legal proceedings should be paramount.

The practical issues that arise with evidence in digital form will always be with us, and increasingly used in automated systems using ‘AI’, as noted by Hugo Rifkind, ‘Horizon was ‘computer says no’ on a vast scale’.

A recommendation to resolve this issue was made to the Ministry of Justice at the request of Alex Chalk MP, who was then a junior justice minister, in 2021. It has yet to be implemented.

Yours,

Stephen Mason and Martyn Thomas

Stephen Mason, joint editor of Electronic Evidence and Electronic Signatures (5th edition, 2021)

Martyn Thomas CBE FREng Emeritus Professor of IT, Gresham College

Stephen believes that the law needs to urgently move into the twenty-first century. In Stephen’s book, Electronic Evidence and Electronic Signatures, a practitioner textbook now in its fifth edition, a team of experts in the field provide a comprehensive overview of electronic evidence and electronic signatures. It is essential reading for anyone who wants to understand more about the role of electronic evidence in the Post Office scandal, how similar issues can, and have, happened elsewhere and why the law on computer evidence must be changed. The book is Open Access and is free to download in PDF format.

Electronic Evidence book cover

Stephen is also the founder and editor of the Open Access journal Digital Evidence and Electronic Signature Law Review, published by the Institute of Advanced Legal Studies (IALS). As Stephen wrote in 2021 for the IALS Annual Review, ‘My previous attempts to persuade the Solicitors Regulation Authority and Bar Standards Board to require the topic of electronic evidence to be taught has met with apparent indifference. Perhaps the Post Office Horizon scandal will cause a change in policy.’

As The Guardian have reported, ‘Mason, along with eight other legal and computer experts, was invited by the government to suggest an update to the law in 2020, following a high court ruling against the Post Office, but the recommendations they submitted were never applied.’ Read the full article here.

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