I have a HUGE problem with this line of reasoning. I believe murderers should be executed as punishment for their heinous crimes, not because society is unable to adequetely incarcerate them. Capital punishment is either right or wrong. The Catholic church seems to say society can only execute people when it can't contain them. Would this logic then allow pro-abortionists to say babies can be aborted when thier mother's can't afford the children? Possibly.
I am fairly certain there have been dungeons since the time of Christ. Since the Catholic Church has approved of the death penalty for 2,000 years, I think JP II was simply wrong when he attempted to "evolve" the church teaching on this subject.
Indeed, in the old days, there were no juries, no DNA testing, and no appeals. The death penalty today is much more just.
I'm afraid I'm not following you here. The Church is talking about sparing lives. The abortionists are talking about destroying lives. Those are opposites. Not all killing is murder. But the deliberate killing of innocent persons is always murder. That's why it cannot be justified under any circumstances: Killing 30 babies every Saturday at Women's Surgi-center or killing 100,000 civilians in Nagasaki or killing sexual rival with a baseball bat.