Question: On February 20, 1987, the Pontifical Council for the Authentic Interpretation of the Code of Canon Law issued an interpretation of Canon 910 §2 which stated that the extraordinary minister of Holy Communion may not exercise his or her function “when ordinary ministers, who are not in any way impeded [qui non sint quoquo modo impediti], are present in the church, though not taking part in the Eucharistic celebration.” An ordinary minister may be impeded if he is not vested, has not been notified that he is to assist in this ministry, or cannot easily approach the sanctuary. In such cases extraordinary ministers of Holy Communion are free to exercise their ministry. The General Instruction of the Roman Missal (GIRM) says when a deacon is present at the celebration of the Eucharist, he should exercise his ministry wearing sacred vestments. I've heard some people interpret this very strictly that the deacon, if present, should always vest and assist. Priests I've talked to would rather have an unvested deacon (as an ordinary minister of Holy Communion) assist with distribution as needed, versus an extraordinary minister of Holy Communion. If a deacon attends Mass, but is not vested and is called on to distribute Communion, it creates a logistical challenge as to when it would be appropriate to put on an alb and stole.