Abolition of death penalty

In New Jersey, death penalty was abolished.It was the first time after judgement of legitimacy. According to the supecial committee in New Jersey, death penalty has not effect to stop murder but has affair of mistake. These days, many countries and states abolish death penalty but in Japan this crime exist even now. Is it right choice? Indeed, it is possible to mistake criminal and it may have no effect to decrease the number of murders. it is very difficult to think.