Alexander Blackman: How should crimes on the battlefield be handled?

UK Prime Minister Boris Johnson has promised to take steps to protect military personnel from what he describes as vexatious legal claims. It’s a controversial stance as armed conflicts, from Northern Ireland to Iraq, have thrown up serious allegations of criminal wrongdoing by soldiers. Former Royal Marine Alexander Blackman was convicted of murder while serving in Afghanistan in 2011. He served three years in prison and, after a long legal struggle, his conviction was reduced to manslaughter. What does his case tell us about morality and accountability on the frontline?