[quote="x1980x, post:1, topic:306677"]
My understanding from having read about Catholic seminary in the past was that seminarians would receive minor orders (e.g. lector), after having made some progress (e.g. passed introductory courses), then would receive ordination as a Deacon (major orders) after some further progress, then would finally graduate and, if is discerned to be the will of God, be ordained. Vatican II's reintroduction of the Permanent Diaconate established a separate process for men who did not intend to become priests to become deacons and serve in that capacity. Before Vatican II, for a long time, the only non-priest deacons were men who were using the diaconate as a way station on their way to becoming a priest. It wasn't an end to itself.
To what extent do these orders have a non-theoretical meaning for men who fail to complete seminary? For example, if a man is admitted to seminary and receives ordination as a Deacon after reaching the appropriate point, and then, as a deacon, fails out of seminary due to poor grades, quits, or is expelled for misbehavior, is he automatically considered a Permanent Deacon or can he function as such while it is determined whether or not he should return to seminary, or does the fact that he is technically a Deacon have only theoretical relevance because he hasn't gone through Permanent Deacon formation (e.g. he could only serve in an emergency)?
To a certain extent, it depends upon why he leaves.
If he leaves on his own, deciding not to become a priest, he actually has a right to continue as a deacon. Here's the canon:
Can. 1038 A deacon who refuses to be promoted to the presbyterate cannot be prohibited from the exercise of the order received unless he is prevented by a canonical impediment or another grave cause to be evaluated in the judgment of the diocesan bishop or competent major superior.
If however, he is dismissed from formation, or there is some impediment preventing him from being ordained a priest, then he can be prohibited from functioning as a deacon. Remember though that he will always be a deacon, but unable to function as one.
If there is such an impediment (preventing priestly ordination) it's highly unlikely that it would not be discovered until after ordination as a deacon. Also very unlikely that an impediment would arise after ordination (say, if he attempts a civil marriage). Unlikely but neither is impossible.
I see where your question is going at the end: if he did not complete "permanent deacon" formation, but only completed "transitional deacon" formation, does that prevent him from functioning as a deacon? Canon law says no. Once he is ordained a deacon, he "is" a deacon, regardless of which formation track he was on at the time of ordination.
In part, that canon protects permanent deacons whose wives die. The bishop can invite the deacon to become a priest (after further training), but cannot compel him to do so by threatening to suspend his diaconal faculties if he does not agree.