This is not correct. The documents issued by the Second Vatican Council do not mandate changes in the placement of the tabernacle. The Constitution on the Sacred Liturgy grants power to national conferences of bishops to adapt sacred furnishings to the needs and customs of their respective regions (Sacrosanctum Concilium 128).
The document referred to was the Instruction on the Worship of the Eucharist Mystery (Eucharisticum Mysterium), a post-conciliar document, issued by the Vatican following the Council. After recommending that the Blessed Sacrament ought to be reserved in a truly prominent location and one suitable for private prayer and devotion, the instruction states, "It is therefore recommended that, as far as possible, the tabernacle be placed in a chapel distinct from the middle or central part of the church, above all in those churches where marriages and funerals take place frequently and in places which are much visited for their artistic or historical treasures" (53).
It goes on to say, "The Blessed Sacrament should be reserved in a solid, inviolable tabernacle in the middle of the main altar or on a side altar, but in a truly prominent place. Alternatively, according to legitimate customs and in individual cases to be decided by the local ordinary, it may be placed in some other part of the church which is really worthy and properly equipped" (54).
The Code of Canon Law states, "The tabernacle in which the Blessed Eucharist is reserved should be sited in a distinguished place in the church or oratory, a place which is conspicuous, suitably adorned and conducive to prayer" (CIC 938:2).
Many church renovations are undertaken under the "authority" of a document titled Environment and Art in Catholic Worship. This document, promoted widely by "liturgical experts," was passed by the American bishops' committee on the liturgy in 1977, but it was never brought before the entire body of bishops for a vote, presumably because its backers realized that it would be voted down.
It has been published anyway in book form, giving many the idea that its recommendations are of binding authority; in fact, it has no authority at all and can be ignored.
In an eyebrow-raising move, the book's editors added an appendix of photographs that showcase renovations even more radical than the text promotes. As Thomas Day, author of Where Have You Gone, Michelangelo?, has noted, the "presider's chair" in the photographs isn't a chair at all--it's a gigantic concrete throne.
Through poor liturgical art and architecture and through a jettisoning of traditional symbols--all advanced by Environment and Art in Catholic Worship--the focus of the Mass shifts from the altar to the priest. (Needless to say, in the photographs tabernacles are well hidden.)