The worst thing about activists like Sister Helen is that they end up doing their cause more harm than good, especially among those of us Catholics who are inclined to view such obvious leftism and heterodoxy with suspicion.
Indeed, it was because of activists like Sister Helen that it took me years to realize that the Church wasn't all that inclined to look positively on the nuclear arms race; and it's because of people like Sister Helen that it also took me years to tease out just what a Catholic ought to be thinking about in terms of the death penalty, too.
Because, of course, the death penalty isn't intrinsically evil. Unlike abortion which is never permissible, the just exercise of the death penalty by lawful civil authorities for the purpose of punishing the guilty has always been, and will always be, morally acceptable.
The Catechism of the Catholic Church puts it this way:
2266 The efforts of the state to curb the spread of behavior harmful to people's rights and to the basic rules of civil society correspond to the requirement of safeguarding the common good. Legitimate public authority has the right and duty to inflict punishment proportionate to the gravity of the offense. Punishment has the primary aim of redressing the disorder introduced by the offense. When it is willingly accepted by the guilty party, it assumes the value of expiation. Punishment then, in addition to defending public order and protecting people's safety, has a medicinal purpose: as far as possible, it must contribute to the correction of the guilty party.67
2267 Assuming that the guilty party's identity and responsibility have been fully determined, the traditional teaching of the Church does not exclude recourse to the death penalty, if this is the only possible way of effectively defending human lives against the unjust aggressor. If, however, nonlethal means are sufficient to defend and protect people's safety from the aggressor, authority will limit itself to such means, as these are more in keeping with the concrete conditions of the common good and are more in conformity to the dignity of the human person. Today, in fact, as a consequence of the possibilities which the state has for effectively preventing crime, by rendering one who has committed an offense incapable of doing harm - without definitely taking away from him the possibility of redeeming himself - the cases in which the execution of the offender is an absolute necessity are very rare, if not practically nonexistent.NT
It is true that generally speaking our use of the death penalty in America today doesn't always appear to meet the prudential guidelines outlined in the Catechism, which I'll summarize as follows:
1. The guilt of the person must be fully determined.
2. Non-lethal means must be insufficient to protect innocent people's lives from the convicted criminal.
3. The non-lethal means must include the opportunity for redemption.
Now, I think that the first criteria is setting a higher standard than our legal notions of "beyond reasonable doubt." That standard, after all, still allows the convicted person to appeal his case. I'm not sure at what point between "beyond reasonable doubt" and catching the criminal red-handed in the process of committing the crime, with the added weight of his own guilty confession, we would find "fully determined," but that's why these are prudential decisions to be applied on a case-by-case basis. However, it can't be overlooked that the death penalty today is too often disproportionately applied not to those whose evidence of guilt is the strongest, but to those who can least afford highly-skilled criminal lawyers to defend them, which is inherently unjust.
The second criteria is the one that many strident death penalty opponents focus on. Surely, surely in America in the twenty-first century our methods of incarceration are sufficient to protect society from those who pose a danger! But as this recent story reminds us, this is not always the case. Even given high-tech security measures and well-guarded prisons, it's possible for some prisoners to pose a threat to other inmates, to guards, and to the public. I recall the news when the so-called "Texas Seven" escaped; I remember reading about the police officer killed by them on Christmas Eve. Of the seven, two were supposed to be serving life sentences; in fact, the man supposed to be the group's leader was serving eighteen life sentences for his crimes. The duty to balance the potential public threat posed by those convicted of serious crimes against the criminal's right to be treated with the intrinsic dignity owed to all human beings is an important and weighty one.
The third point may seem strange at first glance. But consider for a moment the possibility that sometime in the future it might be seriously proposed to replace the death penalty with a life sentence that includes keeping the convicted criminal on some kind of prescription medication that will rob him of his free will and consciousness, making him docile, easily controlled, and no longer a threat to the public, his fellow prisoners or guards, and so on. It seems clear that the Church wouldn't consider this an acceptable alternative to the death penalty, at least not if the medication in question made it impossible for the prisoner to remember his crimes, learn to feel remorse, and seek God's forgiveness for them.
All of this means, of course, that opposition to the death penalty from a Catholic perspective isn't at all in the same category as opposition to abortion. They are not two different sleeves on the same seamless garment; and though at root both are connected to our appreciation of the inherent worth and dignity of all human life we don't do either issue any favor when we try to conflate two such dissimilar matters. Opposing abortion is the duty of all Catholics, who should work to end it and never to support it; opposing the death penalty in general because of our desire to see criminals repentant and working for their salvation as we hope for ours, and mindful of the Church's belief that it is not inherently wrong for the state to choose to impose this penalty under certain circumstances and that we may on occasion disagree with our fellow Catholics about specific criminal cases and whether these meet the criteria outlined above from a prudential standpoint, is also a duty, but a duty of a different sort and degree.
Unfortunately for many pro-life Catholics, the constant attempt to equate abortion and the death penalty as if they were of the same moral weight, or worse, the tendency by some leftist Catholics to oppose with great vigor the death penalty while insisting that their "personal" opposition to abortion should not be imposed upon society, weakens the effect of our efforts to promote the Gospel of Life. To put it in the simplest possible terms, abortion is always wrong, while the death penalty may or may not be wrong in an individual criminal case depending on certain prudential considerations which both justice and mercy compel us to consider.