The life sentence gives the prisoner and opportunity to be proved non guilty. By being put on death sentence a, completely innocent person can be executed. Even though it may cost a little more money, it still allows a more of an accurate tell of what the truth really is. Plus, the ways people are killed when put on death sentence are very fatal. Even if they did a crime to where most think they deserved it, it still is a bit excessive because you never know who could be lying and human memories are just a down right unreliable source for information.
Depending on the crime,and obviously the death penalty or life imprisonment implies that a criminal has committed a crime so perverse that s/he deserves to be punished in such a harsh manner by society. Keyword deserves. One of these crimes is murder, if we permit a murderer to enjoy the rest of his natural life in prison, we allow him or her to enjoy the liberties and freedoms that he denied not only his victim but the victim's loved ones. It is a severe injustice that promotes crime as the criminal knows the worst he can get is life. The death penalty discourages such a mentality and brings caution to all ambitious criminals. Convicted Norwegian far-right mass murderer Anders Behring Breivik Who was given the gift of life imprisonment after murdering in cold blood hundreds of people is causing more pain to those families by appealing against his light sentence,this unrepentant criminal is essentially rubbing it in that all those he murdered deserved it. should the many suffer for the one? The one that took away fathers,mothers,sons,daughters,friends and brothers and sisters?What happens when others follow his example knowing that they will be given life and become heroes? Life imprisonment is more barbaric and inhumane than the death penalty (and also more expensive ) it is a constant reminder to the criminal that society will lock him away for the rest of his life, isn't solitary confinement for life worse than death ? Such a man has nothing to loose and is forced to live life in great despair and often having no remorse for his past deeds. The death penalty is a superior disciplinary tool, an incentive against barbaric and inhumane crime, and a just settlement especially for those who rob the dreams of there victims,who most often than not are probably innocent.
I do see where your coming from, but you seem to completely look over the fact that a lot of people who are but to death sentence end up being innocent but they cant do anything at that point. Its hard to know who is innocent or guilty these days because there is way too much bias towards one side. Also, a lot of people just believe the first thing they hear which in most cases is the wrong standpoint. If nobody will speak with regarding strictly evidence, we cant exactly trust who is guilty or not. Also, people aren't getting truly fair trials in order to give the defendant a honest chance to have people hear their side. I know a fair trial is mandatory but in most cases, the trial in which is said to be fair, really isn't, and most people don't realize that. Whether the bias is coming from the judge, the jury or the general public, its inescapable. There is always some sort of bias in every situation, even some of the simplest situations. Therefor, it causes a lot of incorrect rulings. I can't deal with a person dying for something that they didn't even do.
At least 4.1% of all defendants sentenced to death in the US in the modern era are innocent, according to the first major study (guardian.com) it is unacceptable that an innocent life is lost unjustly. However, out of every 100 people sentenced to death, 96 are Guilty BASED on this study. Should the margin of error of 4% keep the streets loitered with 96% hardcore murderers and unrepentant killers? Obviously the greater good takes precedent as such the notion that an innocent man may be killed hence let all guilty men stay free is dangerous and contributes to the already over crowded prison system. No one is saying that killing the innocent is right but protecting the majority innocent takes precedent over all other considerations. Also death sentences have a period of years between judgement and execution, with the improvements in technology and I must admit with some luck an innocent man will walk easily. And I can not say it is fair but many times the compensation on account of innocence exceeds what the person may have earned outside prison (this is an assumption,it is possible it could be more)
Your argument simply focuses on the rear possibility of innocence, you are essentially saying save 4 and keep 96 alive and sometimes able to continue soiling society with crime. The issue here is not justice or fair trails, it is whether death is a suitable punishment even with the risk that some innocent people pay the price. The system is flawed but it works and any attempt to justify replacing it with a toothless one shall certainly backfire and make a mockery of punishment.
It is simply not valid a reason to say that innocent people MAY get killed, a good solution would be to place personal responsibility on district attornneys if misconduct is discovered, harsh but worth saving an innocent life.
My colleague's argument does not account for the fact that the needs of the many outweigh the needs of the four.