Andrew Goddard - as usual - has an excellent discussion of the Pope's recent move re the death penalty (from admissible to inadmissible), here, with a multitude of links to Catholic writers and theologians. (Liturgy also posts on the decision and has some useful collation of key statements, here).
Goddard's discussion notes the trepidation some commentators have that a shift from admissible here to inadmissible could presage a shift from inadmissible to admissible over there ... if you get my drift.
One issue I am intrigued by, triggered by some things I read on the net before reading the Goddard post, is this: is change to ethical teaching best approached via a "development" conception?
On a development conception we change teaching on X bit by bit, perhaps taking centuries to do so.
An alternative conception could be we simply admit we got it wrong in the past.
With respect to the former: there is a charting of development possible with Catholic teaching about the death penalty, though wise people have pointed out that Francis shift from admissible in narrowly prescribed circumstances (as development previously had done) to inadmissible in all circumstances is not a development but a change. And by "change" those commentators mean, the church effectively now says previous popes/catechisms have been wrong.
With respect to the latter: I would argue that the church universally today recognises that it was previously wrong when it tacitly tolerated let alone explicitly endorsed slavery.
In response to my question, "is change to ethical teaching best approached via a "development" conception?", we could observe that the church - through history - has both developed its ethical teaching and changed its ethical teaching.
What do you think?