Catechism of the Catholic Church §2107 — excerpt
"If because of the circumstances of a particular people special civil recognition is given to one religious community in the constitutional organization of a state, the right of all citizens and religious communities to religious freedom must be recognized and respected as well."
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: DH 6 # 3