The story told in this book of lives ruined, of tenacious journalism, of the role of lawyers in defending their client’s interests, and of judges trying to see justice through a complex thicket of technical details and confusion. It is told by a journalist who, for many years, investigated what may be the largest miscarriage of justice in British history. The broad outline is probably familiar to most with an interest in computers and law: the Post Office prosecuted hundreds of sub-postmasters for alleged theft, false accounting and fraud on the basis of computer evidence that proved unreliable.

It is a story of individuals who were confronted with errors in balancing the day’s transactions on the computer systems in their post offices, and (often reassured by a helpline) pushed a button to agree a final figure that they knew they were incorrect; of a system that was not carefully tested or robust; and of senior management and union representatives who either trusted completely that the information in the database was the only correct representation of the world or chose to act as if it was. It is a story in which the slow progress of the law towards justice eventually vindicates the reputation of some victims of over-zealous prosecution but comes too late for others.

Three experiences from my career made this book particularly resonant for me. When I was an undergraduate, I supported myself by working as a shelf-stocker in a supermarket, and after some time, was ‘promoted’ to checkouts. When it was busy, it could be very tiring. One particular Saturday, I couldn’t balance my till ­– I was short by £20 (which was more than my week’s rent at the time). I was very concerned: having to make this shortfall up from my own resources would put me under financial pressure. More importantly, I could find myself accused of having stolen the missing money. Fortunately, the manager on duty was reasonable, checked my calculations, and re-assured me that I had made a mistake and the till was in order. I clocked out, very relieved. 

Later, in a more professional role, I was the lead software developer for a financial transaction processing system. It was not very complex, but was intended to operate at scale. (Within a few years, it was handling millions of euro annually.) I knew that even minor errors could mount quickly and create significant consequences for my client and my reputation. After nine months of work, my contact point wanted to ‘go live’ as soon as possible, but I insisted on another few months of testing. I was rewarded by discovering a minor but nonetheless consequential error shortly before the system launched. (As far as I know, it has operated without difficulties since.)

Later again, I worked as a researcher in the Supreme Court of Ireland. Much of it was spent reading and writing behind the scenes but I would sit in on interesting cases, either because I had work to do for them or because I knew they were significant. Hearings are rarely dramatic in the way that the media will present it, but with an understanding of the issues and the personalities, even brief exchanges or seemingly casual asides in court can have great importance.

This book is not recommended as bed time reading. The conversational style and the sense that a new revelation is just a few pages away will keep you from putting it down, and the many startling vignettes will make you exclaim in shock and horror, none of which is conducive to sleep. Knowing what it was like to just want to balance a till and go home at the end of a long and tiring day, I found the stories of the individual postmasters compelling and often very sad. Having designed and programmed financial systems, the lack of attention to detail, adequate testing, or even wilful blindness to problems documented here were deeply concerning. The legal aspects of this story are explained clearly for a lay audience, and the courtroom moments towards the end of the book are told in a way that those who have sat through hearings will understand and appreciate. What could be boring and mundane is brought to life. One particular moment involves a lawyer describing reading legal advice to the Post Office on failure by an expert witness to disclose material known to him which undermined his opinion, and thus rendered convictions unsafe, as ‘electrifying’. There are many such scenes in the book, and different readers will find aspects that connect with their own personal and career experiences.

 Academics will find plenty of material for case studies in computer evidence law, contract law, and (outside the law) system design and development. Practitioners will find many cautionary tales. Anyone with an interest in professional ethics (either of managers, lawyers, or software developers) will find much to chew over or debate with students or peers. Every reader with experience in any of the various aspects of modern commercial life described in the book will encounter episodes  that will make them query the overall social utility and value of their respective professions. Journalists, lawyers, and some brave technologist whistle-blowers provided some measure of justice to some of the victims of a significant public scandal but much of this scandal could have been avoided if decision-makers had reflected more on the consequences of their choices. It could also have turned out differently if a variety of individuals had not worked very hard to vindicate the good name of the blameless who were caught up in the epistemological hold of the computer system, with which it becomes ever harder to argue. It is a cautionary tale for our increasingly digitised society. The book is recommended to all audiences, even non-lawyers.

Rónán Kennedy, School of Law, National University of Ireland Galway

About the Book

• Hardback
• Published: 18 November 2021
• ISBN: 9781916302389
• Bath Publishing
• 543 pages