It defies common sense that the taxpayer spend £40,000-plus a year keeping a person in jail whose crimes or mental illness are so great they can never be healed.
Roy Whiting, the man who snatched Sarah Payne off the street, threw her in the back of a pre-prepared van, violated and killed her then buried her in a shallow grave, is never going to be cured.
Peter Sutcliffe, the man who killed 13 women and attacked seven more and brought terror to the north of England for five years, is never going to be safe to walk the streets.
Ian Huntley, Steve Wright, Ian Brady. Beverley Allitt, John Duffy, David Mulcahy, Rose West. None of them are ever, with the best will in the world, going to be able to contribute anything but horror and revulsion to society. It's cheaper to kill them, it's easier, and it avoids the kind of problems you get if you leave them alive.
Problems like Levi Bellfield, the man who killed Milly Dowler, Amelie Delagrange and Marsha McDonnell, suing the Ministry of Justice for £30,000 compo because another prisoner gave him a smack in the face.
Bellfield is a vile creature whose long career of rape, abuse and violence deserves far more punishment than a wallop. I imagine the Dowler family would give their eye teeth for the chance to be alone with him, no questions asked. To hear that the taxpayer will foot not only his legal bill but also that for fighting him, as well as the possible payout if he wins, is almost as bad as hearing he intends to spend the cash on a caravan for the day he hopes to be released.
As Milly's mum Sally said after his conviction: "The length to which the system goes to protect his human rights seems so unfair compared to what we as a family have had to endure."
It is difficult to think of a reason why Bellfield should not be beaten to death with a hammer, much less given the painless exit of a lethal injection.
Except, of course, for the other just-as-logical problems it would create.
What happened when you hanged a man in 1964, the last time we had the death penalty, is different to what would happen today. The appeals process would take a lot longer for a start, cost more, involve Legal Aid, and would inevitably lead at some point to a killer's dependents suing the hangman for damages.
Who do you get to do the job? Difficult to employ someone with the character required to be an emotionless executioner, and judicially tricky to allow a victim's relatives to throw the switch or stick in the needle.
Then there's the question of where you draw the line. We'd all be fine with the idea of killing Bellfield today, but while he's inarguably a nasty man the Milly conviction was on purely circumstantial evidence. It could be overturned. Are we all right with killing him for something we've no independent proof he was responsible for?
So let's just limit it to paedophiles. Except people are labelled as such whether they have raped a child or looked at a picture of someone raping a child. Both are beyond my ken but they're not the same thing. Maybe if we limit it to paedophiles who murder? But there's not as many of them as you think, so is it worth the cost of changing the law?
What about a woman who kills her partner and claims he was violent, like Jane Andrews? What about the likes of Jeremy Bamber who has spent nearly 30 years inside for murdering his family in a case which has since, if you'll pardon the pun, been shot full of holes? What about Barry George, a nutty man arrested in the teeth of a media firestorm who was later freed and declared totally innocent? What about Robert Thompson and Jon Venables, who did dreadful things to three-year-old Jamie Bulger when they were only 10? I wouldn't like to be alone in a room with any of these people, but that doesn't mean they should be dead.
The problem with the death penalty is not just where you draw the line, but who draws it. A bereaved family, as tragic and heartrending as their loss must be, cannot make that decision. A politician who wants votes, a journalist who wants to sell papers, a lawyer trying to make a name for themselves, or even the general public stirred up by a big case, should not make it either. In fact, I cannot think of anyone I would trust to do so.
The point of the death penalty is to deter and to punish. But most paedophiles don't kill, most abuse happens in the home, and most never gets to court. Most will never stop believing that children are sexual creatures. Most murders are a crime of passion, and most serial killers are ill. How can you deter or cure any of those things? Sickos won't care and passion, as has often been pointed out, is ungovernable.
Those against the death penalty say there is no alternative, that jail keeps us safe from people we cannot fix. Yet locking up someone like Bellfield is no punishment at all: the thought of him in a comfy room with an X-Box sticks in my throat.
I don't like just locking him up, and I don't like the idea of killing him. I do like the idea that someone convicted of a heinous crime, once their appeals are exhausted and guilt proven beyond the last shadow of doubt, are stripped of their rights.
No voting. No earning money. No computer. No TV. No books, no newspapers, no bed, no toilet but a hole in the floor. No more lawyers, no exercise, no fresh fruit or sunlight. No talking, no socialising. If Ian Brady wants to go on hunger strike, let him. If Ian Huntley gets his throat cut, let him bleed. Let them be hung upside down for 23 hours a day, let the public in to jeer and chuck vegetables, let them enjoy decades of not having the rights the rest of us enjoy.
Let them die, if it happens. But don't let us become killers.
"An eye for an eye makes the whole world blind."
"Killing people who kill people to prove that killing people is bad. What twat came up with that idea?"