From the wikipedia page "...Although many subpostmasters had reported problems with the new software, and Fujitsu was aware that Horizon contained software bugs

From the wikipedia page "...Although many subpostmasters had reported problems with the new software, and Fujitsu was aware that Horizon contained software bugs as early as 1999, the Post Office insisted that Horizon was robust and failed to disclose knowledge of the faults in the system during criminal and civil cases......" Fujitsu and Post Office management both new of software faults. Either or both of these groups should have dug much deeper. The Post Office Management should have known OR hired Software EXPERTS to advise them on how to determine software reliability. Especially once it was evident a large number of people accused of theft. My Opinion is Post Office Management was negligent, particularly the CEO and other senior managers. ANd they should be charged with criminal negligence. CEO and senior managers are paid "big money" to deal with such companies, they should have dug "much deeper" to investigate, especially since their would have been large numbers who claimed innocence The software company Fujitsu, is also criminal negligence. Producing a financial system and not validating it. The defence lawyers ( maybe with software computer system speciality ) could have asked for test records, test data how the system was validated. That would have been my first question. OK , Fujitsu and Post office management claim system is reliable, WHERE IS THE EVIDENCE OF SYSTEM RELIABILITY. Where are the exact test records and test data to support this claim. Where are the system design documents. Where is the company's bug / issue tracking, reports. How exactly is the software tested? It seems the problem could have been detected at several levels , but for various reasons they all missed. I'm shocked that this issue went on for so long. (There must have good people somewhere , that said nothing, ) My opinion is shaped by my work experience as a software test analysist for many years ( a few decades ) , who has worked on software that does financial transactions, every release ( except ones where change was deemed minor ) of our software was examined by auditors from the government. These government auditors could do anything. ask for design documents, ask for test records. request tests be re run in their presence. That we run certain tests designed by the auditors. Interview any staff about the change. These software audits could be from a few hours to several days , depending on the change. Our company maintained a complete test system of the distributed system for this testing.