Q: When a deacon presides for a Sunday celebration in the absence of a priest, may he use the presider’s chair?
A: Yes. If a layperson presides, he or she does not use the priest’s chair, according to Sunday Celebrations in the Absence of a Priest 24, but a deacon does use it according to SCAP 19.
Q: But look at this: http://www.usccb.org/prayer-and-worship/the-mass/frequently-asked-questions/deacons-at-sunday-celebrations-in-absence-of-priest.cfm
A: Oh. OK, after further review, I see that I was using an older edition of the book Sunday Celebrations in the Absence of a Priest. Indeed, the legislation has changed. Paragraph 24 now says, “Leaving the Priest’s chair vacant, he uses a chair other than the Priest’s as a symbol that the community awaits the presence of the Priest.”