According to the* Constitution on the Liturgy *of Vatican II the Novus Ordo was to remain in Latin with only the Epistle, Gospel and a few prayers said in the vernacular.
*Constitution on the Liturgy *# 36
(1) ** The use of the Latin language, with due respect to
particular law, is to be preserved **in the Latin rites. (2) But
since the use of the vernacular, whether in the Mass, the administration of the sacraments, or in other parts of the
liturgy, may frequently be of great advantage to the people, a
wider use may be made of it, especially in readings, directives
and in some prayers and chants.
Code:
(3) These norms being observed, it is for the competent territorial ecclesiastical authority mentioned in Article 22:2, to decide whether, and to what extent, the vernacular language is to be used.
- A suitable place may be allotted to the vernacular in Masses which are celebrated with the people, especially in the readings and “the common prayer,” and also, as local conditions maywarrant, in those parts which pertain to the people, according to the rules laid down in Article 36 of this Constitution.
Nevertheless care must be taken to ensure that the faithful may also be able to say or sing together in Latin those parts of the Ordinary of the Mass which pertain to them.