Well, Ed, here's the whole section on "Loss of the Clerical State" from the Code of Canon Law. As you can see, it's clear as mud.The basic idea is that priesthood is forever - if it was validly received in the first place. That being said, the priest can be "removed from the clerical state," for the reasons stated above (which are not very clear to me) - and apparently, this can only be done by Rome. A local bishop can also remove a priest's "faculties," thereby removing his permission to function as a priest.
CHAPTER IV : LOSS OF THE CLERICAL STATE
Can. 290 Sacred ordination once validly received never becomes invalid. A cleric, however, loses the clerical state:
- 1ƒ by a judgment of a court or an administrative decree, declaring the ordination invalid;
- 2ƒ by the penalty of dismissal lawfully imposed;
- 3ƒ by a rescript of the Apostolic See; this rescript, however, is granted to deacons only for grave reasons and to priests only for the gravest of reasons.
Can. 291 Apart from the cases mentioned in can. 290, n. 1, the loss of the clerical state does not carry with it a dispensation from the obligation of celibacy, which is granted solely by the Roman Pontiff.
Can. 292 A cleric who loses the clerical state in accordance with the law, loses thereby the rights that are proper to the clerical state and is no longer bound by any obligations of the clerical state, without prejudice to can. 291. He is prohibited from exercising the power of order, without prejudice to can. 976. He is automatically deprived of all offices and roles and of any delegated power.
Can. 293 A cleric who has lost the clerical state cannot be enrolled as a cleric again save by rescript of the Apostolic See.
A later section of the Code gives a list of punishable offenses, but does not specify the punishment. Here's part:The bold print and brown italics are mine - the brown italics indicate an explanation I inserted.
TITLE V : OFFENCES AGAINST SPECIAL OBLIGATIONS
Can. 1392 Clerics or religious who engage in trading or business contrary to the provisions of the canons, are to be punished according to the gravity of the offence.
Can. 1393 A person who violates obligations imposed by a penalty, can be punished with a just penalty.
Can. 1394 ß1 Without prejudice to the provisions of can. 194, ß1, n. 3, a cleric who attempts marriage, even if only civilly, incurs a latae sententiae suspension. If, after warning, he has not reformed and continues to give scandal, he can be progressively punished by deprivations, or even by dismissal from the clerical state.
ß2 Without prejudice to the provisions of can. 694, a religious in perpetual vows who is not a cleric but who attempts marriage, even if only civilly, incurs a latae sententiae interdict.
Can. 1395
ß1 Apart from the case mentioned in can. 1394, a cleric living in concubinage, and a cleric who continues in some other external sin against the sixth commandment of the Decalogue (i.e., sexual immorality) which causes scandal, is to be punished with suspension. To this, other penalties can progressively be added if after a warning he persists in the offence, until eventually he can be dismissed from the clerical state.
ß2 A cleric who has offended in other ways against the sixth commandment of the Decalogue, if the crime was committed by force, or by threats, or in public, or with a minor under the age of sixteen years, is to be punished with just penalties, not excluding dismissal from the clerical state if the case so warrants.
Can. 1396 A person who gravely violates the obligation of residence to which he is bound by reason of an ecclesiastical office, is to be punished with a just penalty, not excluding, after a warning, deprivation of the office.
TITLE VI : OFFENCES AGAINST HUMAN LIFE AND LIBERTY
Can. 1397 One who commits murder, or who by force or by fraud abducts, imprisons, mutilates or gravely wounds a person, is to be punished, according to the gravity of the offence, with the deprivations and prohibitions mentioned in can. 1336. In the case of the murder of one of those persons mentioned in can. 1370, the offender is punished with the penalties there prescribed.
Can. 1398 A person who actually procures an abortion incurs a latae sententiae excommunication.
TITLE VII: GENERAL NORM
Can. 1399 Besides the cases prescribed in this or in other laws, the external violation of divine or canon law can be punished, and with a just penalty, only when the special gravity of the violation requires it and necessity demands that scandals be prevented or repaired.