There’s nothing I can say in support of capital punishment that the bishops haven’t already considered and rejected.
You are in error.
The Bishops have simply accepted anti death penalty claims, without fact checking them, a very bad example for their flock and for the truth. That has been the Bishops MO for decades.
In addition, It is as if the Church didn’t consider that executed murderers cannot harm, again, but that livings murderers can and do.
Why has the Church chosen to depend upon widely varying and error prone incarceration systems, when the reality is that so many innocents are caused further suffering by known unjust aggressors, because of the failings in those systems?
It appears the Catechism’s (& EV) authors never considered the reality of such sufferring. (3&4)
And why has the Church done this when it commands “Preserving the common good requires rendering the unjust aggressor unable to inflict harm.” ? 2265
Here are the known realities of all unjust aggressors, murderers and other violent offenders. They can morally/criminally/spiritually:
(a) improve, which can mean everything in a spectrum from still quite bad to sainthood;
(b) stay the same, a bad result for them and others; or
(c) become worse, a more severe, negative outcome which puts the unjust aggressor and all others even more at risk.
The only way to, humanly, make a criminal “unable to inflict harm” is to execute them.
Rationally, factually, there is no other way.
The Church has reversed its longstanding emphasis on protecting innocents. This Catechism, to the contrary, has decided to give much more deference to guilty murderers than it has to protecting the innocent or defending society.
There are at least four Church recognized foundations for criminal sanction; 1) defense of society against the criminal; 2) rehabilitation of the criminal; 3) retribution or the reparation of the disorder caused by the transgression and 4) deterrence.
There is a 5th, biblical instruction, theology, tradition and reason which must guide the 4 others. They aren’t mentioned, because they are a constant.
All of those foundations are better met with the death penalty than by lesser sanctions.
The complaint that this Catechism has removed just retribution (and therefore, balance, redress, correction, etc.) from punishment is based upon the reality that 2267 has allowed an improper and inaccurate evaluation of secular penal standards to dominate over both just retribution or “The primary scope of the penalty is to redress the disorder caused by the offense” (2266) and Genesis 9:6.
While the first sections of this chapter (through 2266) detail the importance of retribution, as reviewed, above, the later section (2267) provides little time for justice, which must dominate the utilitarian aspect of protection. The Church miscalculates in 2267 and fails to realize the rational reality that innocents are more protected when murderers are executed, even though the Church enforces that reality within 2265.
“While punishment does serve the purpose of protecting society, it also and “primarily” serves the function of manifesting the transcendent, divine order of justice–an order which the state executes by divine delegation.” " . . . it may be argued that such a conception of punishment, rooted in the restoration of moral balance, always presupposes an awareness of the superordinate dignity of the common good as defined by transcendent moral truths." (5)
“Yet the presence of two purposes–retributive and medicinal justice–ought not obscure the priority of assigning punishment proportionate to the crime (just retribution) insofar as the limited jurisdiction of human justice allows. The end is not punishment, but rather the manifestation of a divine norm of retributive justice, which entails proportionate equality vis-à-vis the crime.” “The medicinal goal is not tantamount merely to stopping future evildoing, but rather entails manifesting the truth of the divine order of justice both to the criminal and to society at large. This means that mere stopping of further disorder is insufficient to constitute the full medicinal character of justice, which purpose alike and primarily entails the manifestation of the truth. Thus this foundational sense of the medicinality of penalty is retained even when others drop away.” (6)
Justice is the soul of sanction. All other results - protection, safety and deterrence - although beneficial and desired, are a result of sanction, not the reasons for it.
Rehabilitation/redress/correction/redemption/expiation have a foundation in just retribution, but depend upon the free will choice of the criminal who we hope will, by grace, avail themselves of those choices.
“The Roman Catechism of the Council of Trent” (1566)
“The just use of this power (execution), far from involving the crime of murder, is AN ACT OF PARAMOUNT OBEDINCE” (my emphasis) to this Commandment which prohibits murder. The end of the Commandment is the preservation and security of human life. Now the punishments inflicted by the civil authority, which is the legitimate avenger of crime, naturally tend to this end, since they give security to life by repressing outrage and violence. Hence these words of David: In the morning I put to death all the wicked of the land, that I might cut off all the workers of iniquity from the city of the Lord."
We have another obvious conflict between two standards

a) “PARAMOUNT OBEDIENCE” to God (Trent, 1566) vs man’s accomplishments within the error prone criminal justice system (2267, Catechism, amended 2005).
- Pope John Paul II: Prudential Judgement and the death penalty
homicidesurvivors.com/2007/07/23/pope-john-paul-ii-his-death-penalty-errors.aspx
contd