Each of us is called to respect the life and dignity of every human being. Even when people deny the dignity of others, we must still recognize that their dignity is a gift from God and is not something that is earned or lost through their behavior. Respect for life applies to all, even the perpetrators of terrible acts. Punishment should be consistent with the demands of justice and with respect for human life and dignity.
USCCB, A Culture of Life and the Penalty of Death
"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, non-lethal 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 more in conformity with 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 definitively 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."
The Catholic Church proclaims that human life is sacred and that the dignity of the human person is the foundation of a moral vision for society. All people are created in the image and likeness of God and thus all human life, at all stages, is sacred. This belief is the foundation and root to all the principles of our social teaching (Catholic Social Teaching or CST). In our society, human life is under direct attack from abortion and euthanasia. The value of human life is being threatened by cloning, embryonic stem cell research, and the use of the death penalty. We believe that every person is precious, that people are more important than things, and that the measure of every institution is whether it threatens or enhances the life and dignity of the human person.