Sacramento vs. the Dominicans: why St. Paul would approve
What's unusual here is that the diocese is not suing the province in a civil court, but rather, in an ecclesiastical tribunal. One need not know anything about the merits of the case to say, this is a good move.
St. Paul was infuriated by the spectacle of Christians hauling one another before civil courts for judgment (1 Corinthians 6). Rightly so. Assuming forgiveness, forbearance, or compromise do not resolve concrete disputes among Christians, there should be an alternative to our suing each other civilly and thereby inviting the state to intervene in conflicts among believers.
And there is.
Canon law, the oldest continually functioning legal system in the western world, has long been a forum for the adjudication of complex disputes between Christians, and it remains so now. That canon law is turned to for such service so seldom is truly regrettable.
Here is not the place for a mini-course in canonical procedural law, but I would call attention to 1983 CIC 1400.1, 1: "The object of a trial is: the pursuit or vindication of the rights of physical or juridic persons. . . " and 1491, making rights, not "causes of actions", the key to invoking tribunal authority over given controversies. These two canons support the diocese's decision to turn to Church law for hearing this dispute.
As for precedents for such cases, while pre-codified law is rife with examples, even codified law has seen many such petitions being adjudicated up to the highest levels of the Church judiciary. To verify this, one could simply leaf through the indices of the Roman Rota's annual sentences, or consult directories such as:
Carolus Holbock, Tractatus de Jurisprudentia Sacrae Romanae Rotae juxta decisiones quae hoc sacrum tribunal edidit ab anno 1909 usque ad annum 1946 et publicavit in voluminibus i-xxxviii (Styria, 1957) 400 pp., or Augustine Mendonca, Rotal Anthology, An Annotated Index of Rotal Decisions from 1971 to 1988 (Canon Law Society of America, 1992) 771 pp.
Naturally, to file a case is not to win it; and to be sued is not to be liable. But both parties to this unfortunate dispute can be confident of receiving a fair hearing, and even complimented for setting a good example for the rest of us.