Since I support the “opinion” answer, let me explain why. We have seen this from Cardinal Ratzinger in 2004:
”if a Catholic were to be at odds with the Holy Father on the application of capital punishment … he would not for that reason be considered unworthy to present himself to receive Holy Communion.”
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“There may be a legitimate diversity of opinion even among Catholics about waging war and applying the death penalty”
That is pretty suggestive that we may form our own opinions on this topic but there was also this from the USCCB in 2005 (A Culture of Life and the Penalty of Death):
"The death penalty arouses deep passions and strong convictions. People of goodwill disagree. In these reflections, we offer neither judgment nor condemnation but instead encourage engagement and dialogue, which we hope may lead to re-examination and conversion. Our goal is not just to proclaim a position, but to persuade Catholics and others to join us in working to end the use of the death penalty…"
Can anyone imagine this being said about any Church doctrine: “people of goodwill disagree”? “We offer neither judgment nor condemnation”? “We hope [dialogue] will lead to conversion”? It really seems unimaginable that the bishops would talk this way about any teaching we were obligated to accept. Finally, there is this from Cardinal Dulles, which leaves no doubt about his position: (Catholicism and Capital Punishment, 2001):
"The Pope and the bishops, using their prudential judgment, have concluded that in contemporary society, at least in countries like our own, the death penalty ought not to be invoked, because, on balance, it does more harm than good."
There are a number of scholars both within and outside the Church who support this position and it is certainly the one that makes the most sense to me.
Ender