Catechism of the Catholic Church §2246 — excerpt
It is a part of the Church's mission "to pass moral judgments even in matters related to politics, whenever the fundamental rights of man or the salvation of souls requires it.
This translation is under copyright, so only the cited words are quoted here. Follow the link for the full text. Translation: English translation of the Catechism of the Catholic Church, 2nd ed. (Libreria Editrice Vaticana), as posted at vatican.va.
Also cites: GS 76 # 5