Capital punishment is exercised on mentally ill individuals, it also causes emotional suffering for their families and is applied without taking into consideration the convict's case and situation. Thus, death penalty should be abolished.
The Universal Declaration of Human Rights (1948) says: No one shall be subjected to torture or to cruel, inhuman or degrading treatment or punishment (Article 5)." So how can we explain that each year death penalty is performed throughout the world not observing the individual human rights Moreover, "Everyone has the right to recognition everywhere as a person before the law (Article 6)." Does capital punishment treat offenders as human beings Rather not, I reckon. Instead, the state chooses to punish the villain citizen by killing him.
One of the incontrovertible arguments against the capital punishment is that criminals are also real, human beings like us, who have their lives and families. Many of the serial killers have deep psychological problems and instead of being killed should be put into mental institutions and asylums. We have to wisely consider how we will look at criminals, especially murderers - as evil or sick. This is another very important issue and it seems that society hardly ever reacts reasonably on this.