There is no evidence that the death penalty works. Researchers have concluded that the death penalty doesn’t have any effect on murder rates. Or to be more exact, the researchers haven’t found any evidence either way that the death penalty works, it might deter or it might make no difference, or even increase the homicide rate; the results are inconclusive.
By looking at how previous studies were carried out the researchers noticed that they didn’t take into account the deterrent effect of execution compared to a very long prison sentence, even if it might mean no chance of parole. They also noticed that the previous studies came up with implausible models of how murderers think about the act they are committing and its ramifications.
What the researchers found was that studies into the death penalty only looked at the death penalty in isolation. They did not compare how criminals think about the different punishments and look at whether they would not have carried out their crime if the sentence was death or life. Nor did previous studies use data on actual executions to decide if the death penalty was a deterrent, they only looked into the concept. None seemed to use the fact that only around 15% of death row prisoners are actually executed. With such a low number, potential murderers could easily consider it a worthwhile gamble to take.
When you look at the kind of people who generally commit murders you find that they are in the lower social classes, most likely in gangs. They don’t tend to commit a murder with much pre-planning and are very emotionally charged in the time up to the event. That emotion might mean acceptance into the gang or absolute hatred of the victim because they are in the enemy camp. They don’t think of the consequences of their actions. That’s why they don’t tend to cover their tracks and are usually easily found out, unless the gang culture hides them.
Some of the conclusions that can be gathered from the report are that to be truly effective a) the death penalty must be soon after the sentence has been passed, b) it should be 100%, and c) that it should be public. If a death penalty takes decades before it’s carried out then you pretty much have a life sentence. If there are only a few prisoners who get executed and the rest plea bargain or manage to get their sentences commuted then the death penalty isn’t a certainty but more like a gamble. The same kind of gamble even a burglar takes when picking a house. And if the executions are carried out in secret then society isn’t being told about the possible consequences of committing murder.
But having said that, the death penalty still will not stop all murders. It won’t stop the murders of husbands and wives by the partner which are very highly emotional. It won’t stop gang related murders. And it could increase homicides by those who have nothing to lose.