My thanks to Dr. Peters for obtaining permission to post his 2010 article, "Diaconal Categories and Clerical Celibacy" (Chicago Studies 49, pp 110-116) on his website. I was disappointed I couldn't get my hands on it last year, and am very grateful to be able to read it now.
I completely agree with his initial premise, that the so-called "permanent" and "transitional" distinction in the diaconate is fundamentally inaccurate, and that there is only one order of deacons. His brief sketch of how canon law treats all deacons the same in their canonical obligations and limitations shows how true this is.
I would quibble, though, with what he identifies as the significant difference, which the labels "permanent/transitional" attempt to identify. He says that some deacons (mostly "permanent" ones) are married men, and some (mostly "transitional" ones) are not. But as he then shows, this distinction breaks down rather quickly, not least because there are now also married priests in the Roman Church.
To my mind, the difference in not married vs. unmarried state, but rather the intention (or its absence) to ask the Church to discern a vocation to the presbyterate. So-called "permanent" deacons are, for the most part, "permanently" in their ecclesial rank (i.e. the one order of deacons). So-called "transitional" deacons, again for the most part, enter the diaconal rank already having asked the Church to consider if they have the presbyteral vocation. And nearly always, the Church calls them to Holy Orders as deacons precisely because she does discern their presbyteral vocation, and intends to call them to this rank of the clerical hierarchy in the future. In this sense, these deacons (though of course they never cease to be deacons) "transition" (lit. "go through") to the priesthood. Despite their inaccuracies, the adjectives "permanent" and "transitional" do (badly) describe this difference of intention.
What are the implications of this for our current fracas about Canon 277?
If this is true, then Dr. Peters is not correct to identify the present moment as the "crisis" of the Latin tradition of clerical celibacy. The crisis has been and gone, and this is rather its denouement. The admission of married men to the diaconate, and more recently also to the priesthood in certain circumstances, cannot be a "challenge" to clerical celibacy, since the Church has already passed the judgment that its tradition of clerical celibacy could and would be changed. That judgment came when Lumen Gentium noted the possibility of ordaining married men into the clergy, and Pope Paul VI issued Sacrum Diaconatus, permitting the Church to do so. Once that decision was made, the Church changed the meaning of its tradition of clerical celibacy, and therefore of clerical continence (whatever canonical relationship between these two might obtain).
The 1917 Code of Canon Law held all clerics to celibacy, and in practice married men were not ordained. As Dr. Peters argued in his 2005 article, everyone then understood "clerical celibacy" to mean the same thing as "clerical continence." In 1917, these were not two separate canonical obligations (even though conceptually a necessary distinction is made between them), but one and the same obligation. With the admission of married men into the clergy, and the necessary change of the meaning of the tradition of "clerical celibacy," some necessary change in "clerical continence" must also be made.
Dr. Peters's core argument is that this change came in the form of a new distinction, in the 1983 Code, between celibacy and continence, as no longer the same obligation, but now as two separate obligations. I remain unconvinced by this argument, in part precisely because of how closely "clerical celibacy" and "clerical continence" were tied from the 11th to the 20th century. Given the intensity and unanimity of that tradition for nine centuries, it is simply inadequate to introduce and define this new distinction in such a tepid and ambiguous manner as the current wording of Canon 277.1.
Therefore I still would tend to think that there is a defensible argument to be made, to the effect that, for unmarried clergy (regardless of rank), the Church still interprets "clerical celibacy" and "clerical continence" in the same way it has since the Gregorian Reform (one and the same obligation); and that, for married clergy (regardless of rank), there is a new and separate way of interpreting "clerical celibacy" (married men may be ordained under thus-and-such circumstances, but not remarry after ordination) and "clerical continence" (the details still being worked out in practice, as mentioned previously, but not "perfect and perpetual").