A couple of notes on Piers Morgan's show from Monday night
"305 post conviction since 1989 have been exonerated." These exonerations also involved many crimes that occurred long before 1989. Even just since 1989 there have been over 32 million violent crimes committed between 1989 and 2011. I could look up the number of people convicted over that period of time, but even if it is about six or seven million, the exoneration rate is so trivial the only conclusion is that the legal system has obviously been working very well. It is probably lower than 0.005%. Suppose that only a quarter of those cases have DNA evidence available. The exoneration rate is still no higher than 0.02%. To put it differently, at least over 99.98% of the violent criminals were guilty. That is not perfect, but it is hard to think of a system that has that low of an error rate.
The saving money claim from eliminating the death penalty is completely specious. One thing that Ms. Clifton didn't include in her numbers is that there are plea bargains that occur because prosecutors have the death penalty as a potential threat. If someone is obviously guilty of a murder and he is going to get life in prison either way, the criminal is going to trial. It gets him out of prison for a week or two and he gets something different to do. Murder trials, even when the penalty involves life in prison, are extremely costly.
On the gun issue, I would have said: the murder rates vary across countries for lots of reasons, but one thing is clear: gun bans cause murder rates to rise. They still might be lower than the US, but they were even lower before they had those gun control laws.