The Post Office Horizon IT scandal and the presumption of the dependability of computer evidence

Abstract

The Post Office Horizon scandal attracted my interest because of my extensive experience in IT audit and software testing. I have worked on fraud investigations, and also on developing and testing complex financial systems. The Horizon case covered many issues of which I have experience. I was dismayed at the Post Office’s poor control over their systems and their unprofessional conduct in investigations. However, the presumption of computer dependability, which both they, and the courts, relied upon to secure convictions, truly shocked me. All of my experience has taught me that this presumption is naïve and unjustifiable. This is a personal response to the Post Office Horizon scandal.

Index words: Post Office Horizon scandal; fraud investigations; poor control; presumption of computer dependability