A central aspect of the social teaching of the Catholic Church is that it remains congruent with its ancient roots, yet its support for capital punishment has been battered in recent decades to the point that large sections of the faithful believe the Church is against capital punishment, which is not true, as the Catechism teaches:
“Capital Punishment
“2266 The State's effort to contain the spread of behaviors injurious to human rights and the fundamental rules of civil coexistence corresponds to the requirement of watching over the common good. Legitimate public authority has the right and duty to inflict penalties commensurate with the gravity of the crime. the primary scope of the penalty is to redress the disorder caused by the offense. When his punishment is voluntarily accepted by the offender, it takes on the value of expiation. Moreover, punishment, in addition to preserving public order and the safety of persons, has a medicinal scope: as far as possible it should contribute to the correction of the offender.
“2267 The traditional teaching of the Church does not exclude, presupposing full ascertainment of the identity and responsibility of the offender, recourse to the death penalty, when this is the only practicable way to defend the lives of human beings effectively against the aggressor.
"If, instead, bloodless means are sufficient to defend against the aggressor and to protect the safety of persons, public authority should limit itself to such means, because they better correspond to the concrete conditions of the common good and are more in conformity to the dignity of the human person.
"Today, in fact, given the means at the State's disposal to effectively repress crime by rendering inoffensive the one who has committed it, without depriving him definitively of the possibility of redeeming himself, cases of absolute necessity for suppression of the offender 'today ... are very rare, if not practically non-existent.” (Catechism #2266-2267)
The public still is supportive of its proper use, as this article notes.
An excerpt.
“When polls correctly ask about true capital, death penalty eligible murders, support is around 80%.
“Most familiar polls wrongly ask a variation of "Do you support the death penalty for murder?", usually getting replies in the 60-75% range.
“However, in the US, the death penalty is only allowed for those who commit capital murders. Therefore, all polls, which only refer to murders are irrelevant when asking about death penalty support.
“Death penalty support is much deeper and much wider than we are often led to believe.
“Death penalty support for relevant capital, death penalty eligible murders
“81% of the American people supported the execution of Timothy McVeigh, with only 16% opposed. "(T)his view appears to be the consensus of all major groups in society, including men, women, whites, nonwhites, "liberals" and "conservatives." (Gallup 5/2/01).”