I would first look at the death penalty system in action in the US, where violent crime rates are higher.
For the worst crimes, life without parole is better, for many reasons. Iรขโฌโขm against the death penalty not because of sympathy for criminals but because it isnรขโฌโขt effective in reducing crime, prolongs the anguish of families of murder victims, costs a whole lot more than life in prison, and, worst of all, risks executions of innocent people.
The worst thing about it. Errors:
The system can make tragic mistakes. In 2004, the state of Texas executed Cameron Todd Willingham for starting the fire that killed his children. The Texas Forensic Science Commission found that the arson testimony that led to his conviction was based on flawed science. As of today, 138 wrongly convicted people on death row have been exonerated. DNA is rarely available in homicides, often irrelevant (as in Willinghamรขโฌโขs case) and canรขโฌโขt guarantee we wonรขโฌโขt execute innocent people. Capital juries are dominated by people who favor the death penalty and are more likely to vote to convict.
Keeping killers off the streets for good:
Life without parole, on the books in most states, also prevents reoffending. It means what it says, and spending the rest of your life locked up, knowing youรขโฌโขll never be free, is no picnic. Two big advantages:
-an innocent person serving life can be released from prison
-life without parole costs less than the death penalty
Costs, a surprise to many people:
Study after study has found that the death penalty is much more expensive than life in prison. Since the stakes are so high, the process is far more complex than for any other kind of criminal case. The largest costs come at the pre-trial and trial stages. The tremendous expenses in a death penalty case apply whether or not the defendant is convicted, let alone sentenced to death. The tremendous expenses in a death penalty case apply whether or not the defendant is convicted, let alone sentenced to death.
Crime reduction (deterrence):
The death penalty doesn't keep us safer. Homicide rates for states that use the death penalty are consistently higher than for those that donรขโฌโขt. The most recent FBI data confirms this. For people who lack a conscience, fear of being caught is the best deterrent.
Who gets it:
Contrary to popular belief, the death penalty isn't reserved for the worst crimes, but for defendants with the worst lawyers. It doesn't apply to people with money. Practically everyone sentenced to death had to rely on an overworked public defender. How many people with money have been executed??
Victims:
People assume that families of murder victims want the death penalty imposed. It isn't necessarily so. Some are against it on moral grounds. But even families who have supported the death penalty in principle have testified to the protracted and unavoidable damage that the death penalty process does to families like theirs and that life without parole is an appropriate alternative.