Catechism of the Catholic Church §1902 — excerpt
Authority does not derive its moral legitimacy from itself. It must not behave in a despotic manner, but must act for the common good as a "moral force based on freedom and a sense of responsibility":
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 74 # 2 · St. Thomas Aquinas, STh I-II, 93, 3, ad 2