As software spreads from computers to the engines of automobiles to robots in factories to X-ray machines in hospitals, defects are no longer a problem to be managed. They have to be predicted and excised. Otherwise, unanticipated uses will lead to unintended consequences. For proof, look no further than the cancer patients in Panama who died after being overdosed by a Cobalt-60 radiotherapy machine. Or ask the technicians who plugged data into the software that guided that machine, and are now charged with second-degree murder.