Governments get their just powers from the consent of the governed. The legitimate powers of a government come from putting into a common pot certain natural rights which the individual may not be able to exercise fully. The individual still holds these rights, but he lends them to his agent, the government. (Paine)
Can, then, a government legitimately do what the individual cannot? It cannot.
The principal task of a government is to secure the rights of the people. Taking a life is infringing the inalienable right to life of the individual. So when the government takes the life of an individual, it is acting contrary to its task and without the legitimate power to do so. Since individuals have no right to take human life, individuals cannot put that right into the "common pot" of which Paine speaks.
A society which views taking human life as an acceptable solution to complex problems is one which values expediency above fundamental human rights.
A government which takes the lives of its citizens is not fulfilling its mandate. Nor does it have just powers to take lives.
A people which applauds the taking of human life teaches its younger members that life may be taken.
A society whose members think the death penalty actually deters violent crime is one which prefers to ignore the evidence. There is no provable link between the death penalty and a decrease in violent crime.
Capital punishment - of the innocent, of the retarded, of the mentally ill, of juveniles, of a Jeffrey Dahmer, of any human being - is an act unworthy of a civilised people.
Justice requires that a person who infringes the rights of another pay compensation to the victim. The government has the legitimate power to exact this compensation. However, the death penalty is not legitimate compensation, since the victim (or his heirs) receives nothing but the satisfaction of revenge.
A person or group of people who choose no longer to associate with or risk the danger to their rights from another who has seriously infringed rights in the past have the right to protect themselves. This right takes the form of ostracism.
The fact that innocent people are executed is sufficient rebuttal for any argument in favour of capital punishment which is based on a demand for "justice".
The "necessary deterrent" argument can be seen to be without merit when one looks at crime statistics in the US and compares them with those of Western-European countries. It seems to me safe to say that capital punishment isn't deterring young people from a life of crime. It also seems to me that some young people are getting the message (and applying it in their lives) that taking lives is justifiable problem-solving.
In Practice"Judges in Houston, Texas, have repeatedly appointed one local lawyer who is famous for hurrying through trials like 'greased lightning' to represent indigent defendants. Ten of his clients have been sentenced to death. During one death-penalty case, he fell asleep on several occasions. Nevertheless, the death sentence was upheld on appeal and the defendant has since been executed.
"The Supreme Court has ruled that appeals based on lawyer error must prove not only that a defence lawyer was incompetent, but that his incompetence changed the outcome of the trial. Proving such a negative is often impossible. Lower courts have used this ruling to uphold convictions, even in death-penalty cases, in which the defence lawyer was drunk, asleep during the trial or completely ignorant of the relevant law."
"Too poor to be defended" The Economist April 11th, 1998
"Between 1979 and 1989 ... Fred Zain, a state trooper working in the West Virginia state police crime laboratory, falsified results of blood tests in as many as 134 cases. He then moved to Texas, where he continued to fake his results, sometimes in capital cases, until he was sacked in 1993. Ralph Erdmann, a pathologist, faked over 100 autopsies, also in Texas and sometimes in capital cases. His testimony helped to secure as many as 20 death-penalty convictions. And the New York state police department suffered from a rash of fingerprint fakes in the 1980s that affected more than 40 cases."
"Whose body of evidence?" The Economist, July 11th 1998