I think there are exceptional crimes for which the death penalty is the best form of punishment, but I don't know the best way to execute it. People who are convicted of mass murder do not deserve to live on hard-earned taxpayers money for the rest of their lives. However, if the death penalty is imposed then I think the decision should always be sent to a higher court for authorisation (eg, in England and Wales it should either gain approval from the Court of Appeal or Supreme Court).