The Apostolic Letters alone may be ex cathedra documents, and may have the privilege of infallibility, if the matter admit of it.
His pronouncements are held to be infallible when he defines a doctrine concerning faith or morals ex cathedra to be held by the universal church (see Infallibility and Vatican Council).
The second and decisive victory followed at the Vatican Council (1870), which, at the cost of a small secession of distinguished men, declared the pope personally infallible (see Infallibility) and irreformable as often as he rules ex cathedra points of faith or morals.
At the feasts of St Peter in Cathedra and the Conception and Nativity of the Blessed Virgin.
It was provided that the hundred court of Powdershire should always be held there and two fairs at the feasts of St Peter in Cathedra and St Barnabas, both of which are still held, and a Tuesday market (now held on Friday) and that it should be a free borough rendering a yearly rent to the earl of Cornwall.
The pope when teaching ex cathedra acts as head of the whole episcopal body and of the whole Church.