Catechism of the Catholic Church §884 — excerpt
"The college of bishops exercises power over the universal Church in a solemn manner in an ecumenical council." But "there never is an ecumenical council which is not confirmed or at least recognized as such by Peter's successor."
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: CIC, can. 337 # 1 · LG 22