Deacon Greg Kandra (see link at lower right) brought to my attention a blog post by Fr. Zulsdorf about the whole thing of permanent deacons and clerical attire.
Permanent deacons are clerics of the Church. Same as transitional deacons, priests and bishops. We have received the one Sacrament of Holy Orders that other clerics have received. Because of our station in life, to live in the secular world while bridging that world with the holy and the Church, canon law has exempted us from the obligation to wear clerical attire. Various dioceses have differing norms as to the wearing of the Roman collar by permanent deacons, which leads to some confusion among the faithful.
Fr. Z’s post is interesting and Iwould suggest you take the time to read it. Log on to: Fr. Z for the whole discussion.