There have been 21 General Councils in the history of the Church. A Council is called general or ecumenical when it is composed of Bishops from the whole world (oikoumene). These Bishops, the successors of the Apostles, issue decrees, which - if confirmed by the Pope - are infallible declarations of Christian Truths.

However, for clarity's sake, a distinction must be made between the terms infallible and inspired. Inspiration is a positive charism. An inspired document, such as the books of Sacred Scripture, is authored by the Holy Ghost through human authors. As the very Word of God, an inspired document is totally inerrant, for God is Truth itself, and cannot err. Infallibility, on the other hand, is a negative charism. An infallible document (or person, as in the Pope) is protected by the Holy Ghost from erring when solemnly pronouncing, declaring, or defining matters of Faith or Morals.

Therefore, when a General Council defines some matter of Faith and Morals or condemns a certain position, it cannot be in error. Council documents are not totally inerrant, however, as they can contain errors on matters unrelated to Faith and Morals (pastoral matters, for instance). The Venerable John Henry Cardinal Newmann, in his Letter to the Duke of Norfolk, states:

Nor is a Council infallible, even in the prefaces and introductions to its definitions. There are theologians of name, as Tournely and Amort, who contend that even those most instructive capitula passed in the Tridentine Council, from which the Canons with anathemas are drawn up, are not portions of the Church's infallible teaching; and the parallel introductions prefixed to the Vatican anathemas have an authority not greater nor less than that of those capitula.