A good article -
"The Death Penalty is a Pro-Life isse"
(from the USCCB)
"All Christians and people of good will are thus called today to struggle not only for abolition of the death penalty, whether it be legal or illegal and in all its forms, but also to improve prison conditions, out of respect for the human dignity of persons deprived of their liberty. And this, I connect with life imprisonment. Life imprisonment is a hidden death penalty." ~ Pope Francis
Catholic teaching offers a unique perspective on crime and punishment. It begins with the recognition that the dignity of the human person applies to both victims and offenders. It affirms our commitment to seek justice, comfort and support victims and their families, while acknowledging the God-given dignity of every human life, even for those who do great harm. Catholic teaching on human life is rooted in the belief that all life has inherent dignity and is a gift from God that must be respected and defended from conception until natural death.
In his encyclical The Gospel of Life, Pope John Paul II challenged followers of Christ to be “unconditionally pro-life.” He reminded us that “the dignity of human life must never be taken away, even in the case of someone who has done great evil. Modern society has the means of protecting itself, without definitively denying criminals the chance to reform” (Gospel of Life, 27).
The Catechism of the Catholic Church explains that “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, non-lethal means are sufficient to defend and protect people's safety from the aggressor, authority will limit itself to such means” (CCC, 2267). The test of whether the death penalty can be used is not the gravity of the offense, but whether it is absolutely necessary to protect society. The Catechism adds that today “the cases in which the execution of the offender is an absolute necessity ‘are very rare, if not practically nonexistent’” (CCC, 2267).
In 2005, the Catholic bishops of the United States issued, A Culture of Life and the Penalty of Death. In the document the bishops stated that the gift of life must be respected and protected; “that every life is a precious gift from God (see Gn 2:7, 21-23) and that we are all created in God’s image and redeemed by Jesus Christ, who himself was crucified. They acknowledged that sentences such as “life in prison without parole” provide non-lethal alternatives and called for an end to the use of the death penalty in the United States, stating “it is time for our nation to abandon the illusion that we can protect life by taking life.”
“Ending the death penalty would be one important step away from a culture of death and toward building a culture of life.” (United States Catholic Bishops, 2005. A Culture of Life and the Penalty of Death)