Proclamation of the Gospel by the Laity

Is it appropriate for a lay person to proclaim the Gospel reading at a liturgical celebration?

Among the duties proper to the deacon is the proclamation of the Gospel (See General Instruction of the Roman Missal, nos. 175 and 212; introduction to the Lectionary for Mass, no. 50; see Ceremonial of Bishops, no. 24). In the absence of a deacon, a priest may proclaim the Gospel (See General Instruction of the Roman Missal, no. 212, introduction to the Lectionary for Mass, no. 49).

In the absence of a priest or deacon, several of the liturgical books make provisions for a lay minister to proclaim the Gospel, most notably Sunday Celebrations in the Absence of a Priest and the Book of Blessings. The Introduction to the Book of Blessings addresses the question most directly:

[W]henever a priest is present, it is more fitting that the office of presiding be assigned to him and that the deacon assist by carrying out those functions proper to the diaconate. (no. 18)

Therefore, in the presence of a bishop, priest, or deacon, it is not permitted for a lay person to proclaim the Gospel or indeed to fulfill any of the functions proper to their offices. This, of course, reflects the ancient tradition of the Church as expressed by the fathers of the Second Vatican Council:

In liturgical celebrations each person, minister or layman, who has an office to perform, should do all of, but only, those parts which pertain to his office by the nature of the rite and the principles of liturgy. (Sacrosanctum Concilium, art. 28)

May a lay reader take the part of the Christ in the reading of the passion narrative during Lent and the Triduum, or is this role reserved to the priest?

The rubrics for Palm Sunday and Good Friday are quite clear on this question, as reflected in the 1988 Circular Letter Concerning the Preparation and Celebration of the Easter Feasts from the Congregation for Divine Worship and Discipline of the Sacraments:

The Passion narrative occupies a special place. It should be sung or read in the traditional way, that is by three persons who take the part of Christ, the narrator and the people. The Passion is proclaimed by deacons or priests, or by lay readers; in the latter case, the part of the Christ should be reserved to the priest. (no. 33)