Who Can Do What?

[NewEnglandPriest]

Getting back to the question, afaik, all of the liturgies in the Apostolic churches (Eastern & Roman Catolicism; Oriental & Eastern Orthodoxy, etc.) presume that a deacon is present, and have a presribed role for him.

That would be more so with the Eastern Churches than the Latin Church. Deacons are a restored order in the West and are just now becoming settled in their roles. The liturgical documents of the Latin Church are filled with the statements “if a Deacon is present…” thus its not presumed.

Most (all?) permit a priest to exercise the deacon’s portions if none is present (e.g., reading the Gospel, litanies, some of the exhortations), but this should not happen if a deacon is present.

When it comes to the Gospel while the Deacon should be the one to read it, in practice its really the presider’s call. Some priests like to read the Gospel if they’re preaching.

Similarly, deacons and priests should not take the lay roles when a lamany is present who can fulfil the role.

Indeed, but at many a funeral if I didn’t say the lay responses no one would, lol…