Black’s US lawyers raised concerns that his heart implant could shock him back to life, leading to undue suffering.

Byron Black was executed after a back-and-forth in court over whether officials would need to turn off his implantable cardioverter-defibrillator, or ICD. Black, 69, was in a wheelchair, suffering from dementia, brain damage, kidney failure, congestive heart failure and other conditions, his attorneys have said.