Five days after Vatican I had passed Pastor Aeternus, Blessed John Henry Newman our Patron felt that there were factors in favour of suspending judgement on its validity as coming "to me with the authority of an Ecumenical Council". At least 'moral' unanimity seemed necessary for validity, and the 'inopportunist' minority of more than eighty had left Rome before the vote. It all depended on what that minority now did: if they "allege in detail acts of violence and deceit used against the Fathers, if they declare they have been kept in the dark and been practised on, then there will be the gravest reasons for determining that the Definition is not valid." If, on the other hand, they failed to persist in united opposition as a body, then there could be said to have been moral unanimity and there would be no justification for resisting the definition. Finally, and most important, "if the definition is eventually received by the whole body of the faithful ... then too it will claim our assent by the force of the great dictum 'Securus judicat orbis terrarum' ... the general acceptance, judgement of Christendom" was "the ultimate guarantee of revealed truth".
It will be remembered how worried Paul VI was at the size of the vote against Dignitatis humanae, and the pressure brought to bear upon the minority. Who knows whether there may one day be another Ecumenical Council; who knows if an aggressive insolent faction within it might be dominant. We ... I mean, the whole Church ... needs to remember these 'technical' points.
The first paragraph is adapted from Ker's biography of Blessed John Henry Newman.