For the past 20 years UK Post Office employees have been dealing with a piece of software called Horizon, which had a fatal flaw: bugs that made it look like employees stole tens of thousands of British pounds. This led to some local postmasters being convicted of crimes, even being sent to prison, because the Post Office doggedly insisted the software could be trusted. After fighting for decades, 39 people are finally having their convictions overturned, after what is reportedly the largest miscarriage of justice that the UK has ever seen.