USCCB’s FAQ about the Catechism:
16. What is the doctrinal or teaching authority of the Catechism?
The Catechism is part of the Church’s official teaching in the sense that it was suggested by a Synod of Bishops, requested by the Holy Father, prepared and revised by bishops and promulgated by the Holy Father as part of his ordinary Magisterium. Pope John Paul II ordered the publication of the Catechism by the Apostolic Constitution, Fidei Depositum, on October 11, 1992. An apostolic constitution is a most solemn form by which popes promulgate official Church documents. The new Code of Canon Law, for example, was promulgated by the Apostolic Constitution, Sacrae Disciplinae Leges. In Fidei Depositum, Pope John Paul II said, “The Catechism of the Catholic Church, which I approved June 25th last and the publication of which I today order by virtue of my Apostolic Authority, is a statement of the Church’s faith and of catholic doctrine, attested to or illumined by Sacred Scripture, the Apostolic Tradition, and the Church’s Magisterium. I declare it to be a sure norm for teaching the faith and thus a valid and legitimate instrument for ecclesial communion.” John Paul II also stated that the Catechism “is given as a sure and authentic reference text for teaching Catholic doctrine.”
17. Is the doctrinal authority of the Catechism equal to that of the dogmatic definitions of a pope or ecumenical council?**
By its very nature, a catechism presents the fundamental truths of the faith which have already been communicated and defined. Because the Catechism presents Catholic doctrine in a complete yet summary way, it naturally contains the infallible doctrinal definitions of the popes and ecumenical councils in the history of the Church. It also presents teaching which has not been communicated and defined in these most solemn forms. This does not mean that such teaching can be disregarded or ignored. Quite to the contrary, the Catechism presents Catholic doctrine as an organic whole and as it is related to Christ who is the center. A major catechism, such as the Catechism of the Catholic Church, presents a compendium of Church teachings and has the advantage of demonstrating the harmony that exists among those teachings.
The Catechism is part of the Ordinary Magisterium. It is infallible in as much as it refers to infallibly defined doctrines (either through a Pope or a Council). In matters that have not been infallibly defined it represents the current definitions of those matters, however further (more detailed) definitions on those matters may be given by a future Pope or Council.