Those convinced that the postconciliar Church has repudiated its own moral-theological tradition often point to its apparent reversal on ecumenism or religious liberty as proof of their claims. Personally, I see its incoherence on the issue of capital punishment far more damning in this regard.
Here are two useful articles from my favorite modern apologist, Edward Feser, on the topic. In the first, he defends the moral liceity of the death penalty in terms of natural law. In the second, he blasts the ambiguity and equivocation of those clergy eager to chuck the Church’s historical teachings in their zeal to align themselves with the leftist zeitgeist. In the latter article, Feser ultimately concludes that the Church’s supposed opposition to the death penalty in the present age has been badly exaggerated; but it’s telling that the Church is quick to speak in terms that can be so easily misconstrued and slow to correct those misconstructions.
Which reminds me of a conversation I had with a Franciscan on the topic not long ago. I voiced my dislike of the Catechism of the Catholic Church, which is bulky, difficult, terminologically ham-handed, obscurantist, and peppered with passages plucked out of badly-needed context from papal encyclicals. Too many Catholics have read, for instance, its treatment of “conscience” and walked away from it with the impression that the Church gives us free license to dissent willy-nilly from teachings held since the dawn of the faith — and then proceeded to do exactly that. The exasperated Franciscan rolled his eyes and said, “That’s because the Catechism isn’t for the laity. It’s for the theologians!” Which is rather the problem, isn’t it?