In 2004 Cameron Todd Willingham was executed by lethal injection for the murder-by-arson of his two children. He is now widely recognised as having been innocent - leading arson experts agree that the "finding of arson could not be sustained". The fire was an accident, but it cost Willingham his life.
Since 1973 138 people have been sentenced to death in the United States before being subsequently exonerated. That is 138 people who, were it not for the benefit of science - and the work of people investigating their story and advocating on their behalf - would today be dead. They would have been killed by their own government for doing absolutely nothing wrong.
These exonerated people were 'lucky'. No death penalty system could be constructed anywhere in the world that would not put innocent people at risk of execution. Bring back the death penalty in the UK and you wouldn't only execute the occasional person whose guilt you could prove without any shadow of a doubt. What you would do is construct an entire system - a death penalty machine into the clutches of which innocent people would fall and be swallowed whole.
Did I say swallowed whole? I meant mangled, brutally, to death. Every single method of execution is horrific. Some countries shoot people twice in the back of the head. Some use hanging, some public stoning. Even in the US which uses so-called 'humane' lethal injections, the process is gut-wrenching and botched executions are common. The prisoner is strapped to a gurney as large doses of chemicals - first to sedate and then to kill - are pumped into their body. That is after the prison officials have found a vein. If the prisoner is lucky, the vein comes up easily. If not, the prisoner is stabbed repeatedly with a needle until it finally meets their blood stream. Once the chemicals start pumping, the prisoner does not just slip into a deep sleep. Executions can be violent and often the prisoner is in excruciating pain before they are finally put out of their misery.
Even if you are not persuaded by arguments of humanity, the death penalty makes absolutely no economic sense. The average cost of defending a person facing the federal death penalty in the US is $620,932, about eight times that of a federal murder case in which the death penalty is not sought. An assessment of the death penalty in California found that since 1978 the cost of the death penalty had reached more than $4billion. Four billion dollars!
The death penalty in the UK would cost you, the tax payer, a fortune. And yet it would target those people who have no fortune at all. It is the great irony of capital punishment: those without the capital get the punishment. The death penalty kills those people already at the very margins of society, those who have fallen through the cracks. Anyone on death row for murder in the US is a person of low income. And in places like Pakistan and South East Asia where people are on death row for drugs charges, these individuals are never kingpins running vast narcotics operations. They are vulnerable - or, worse, entirely innocent - drug mules.
Never has an argument been put forward that convinces me bringing back the death penalty in the UK would make this country a better or indeed a safer place. A recent study in the US by the National Research Council concluded that there is absolutely no evidence the death penalty deters crime. And American states practicing capital punishment have murder rates at least 48% higher than the states with no death penalty.
If we say that killing people is wrong - and I think few would argue otherwise - it is no less wrong for the State to kill than for an individual to do so. The death penalty damages all those caught up in its barbarism - those killed and those people doing the killing at the government's behest. In countries that use the firing squad, one bullet is always kept blank so that the executioners can never be sure their bullet was the devastating shot, in order to keep them from going mad. The death penalty would uncivilise our whole society, not just a few individuals.
And yet still I always come back to the most devastating fact of them all. If the government starts killing people it will, it is certain, eventually kill an innocent person. I certainly don't want that on my conscience. Do you?