Rishi Sunak has announced plans for new legislation to clear the names of subpostmasters wrongfully convicted because of faulty accounting software.The prime minister said the Post Office Horizon scandal was “one of the greatest miscarriages of justice in our nation’s history”.Blanket legislation to exonerate subpostmasters convicted in England and Wales will be introduced within weeks.The scale of the scandal has prompted the government to adopt the unconventional approach of new legislation, rather than requiring individuals to challenge their convictions.Here, The Independent takes a look at the key questions around the scandal.