Indeed. You can never be 100% sure of guilt all the time. If you have the death penalty, you will kill innocent people, that is a logical consequence.
There's also the pragmatic view that execution is simply too expensive considering the due process requirements.
Implementing a death sentence has its own complications. The judgement of the defendant has to be by people who are not against a death sentence yet deliver justice with the same consistency as other people making the judgement and also gross under representation of groups must be avoided to prevent some people feeling alienated or unjustly placed within a system built for our comfort and protection.
The US uses a 'death qualified Jury' system. This is where there are a few requirements to qualify for the jury. The requirements are obvious and seem simple but create its own bias.
From Wiki:
A death-qualified jury is a jury in a criminal law case in the United States in which the death penalty is a prospective sentence. Such a jury will be composed of jurors who:
-Are not categorically opposed to the imposition of capital punishment;
-Are not of the belief that the death penalty must be imposed in all instances of capital murder—that is, they would consider life imprisonment as a possible penalty.
The creation of such a jury requires the striking during voir dire of jurors who express opposition to the death penalty such that they are unable or unwilling to set aside personal, moral, or emotional objections toward the supporting of a death sentence, and is designed to produce a fair and impartial jury of which the members will fairly consider all options, including the death penalty and life imprisonment.
Expressing opposition to the death penalty does not automatically disqualify a juror. A party may attempt to rehabilitate the juror by asking questions as to whether, personal convictions notwithstanding, they might consider the death penalty. A juror who expresses exorbitant support for the death penalty who would thus otherwise be struck may be rehabilitated should they state a willingness to consider life imprisonment.
And a bit about its Bias:
The bias imposed by the rule goes beyond the application of the death penalty itself. Several studies have found that death-qualified juries are made up of fewer women and minorities. Death-qualified juries are often criticized because they have a similar effect as excluding jurors based on race or gender,[4] which intentional exclusion, in Batson v. Kentucky in 1986, was held as inconsistent with the Equal Protection Clause of the Fourteenth Amendment.
Empirical evidence adduced in Lockhart also has shown that death-qualified juries are more likely than other jurors to convict a defendant.[5] That is, death-qualified jurors are more likely than non-death-qualified jurors to vote for conviction when assessing the same sets of facts. It is argued that since death-qualified juries overrepresent these groups there is a propensity to render guilty verdicts on cases of any type, including those in which the death penalty is not considered.
There is a lot more out there on the inconsistencies of conviction compared to cases where the death penalty is not involved.
I am not opposed to the idea of death as a method to keep harmful members of society from the public, it is just i cannot think of any method of implementation which is both just and fair. The US system is horrible for example.
I think the biggest improvement to our society today however would be the re-introduction of corporal punishment.
People deemed deserving of such punishments are the ones that commit the sort of crimes where severity of getting caught makes little difference, as they never plan or expect to get caught. A guy who plans on stealing a car is not going to be less likely to steal it, if his potential punishment of x years in prison turns into x years +10 lashes. People like that would just think, 'well, i just have to try extra hard not to get caught!'
