ARTI INDECOROSE. — These are the professions or trades so called in the CIC (can. 138), whose exercise is expressly forbidden to clerics because it is considered unbecoming to their state.
The legislator does not specify which arts should precisely be considered indecorous. One must resort to the sources, from which it appears that the prohibition does not concern only certain arts properly speaking, such as that of the comedian, stage or film actor, dancer, juggler, street musician, magician, etc., but also extends to certain trades, such as that of butcher, tavern keeper, public vendor, drover, professional hunter and others, which, although honorable for a certain class of lay people, are nonetheless unsuitable for the clerical state.
The indecorous arts should not be confused with liberal arts and professions (such as, for example, the profession of physician-surgeon, lawyer and procurator, notary, public and private administrator, etc.), which, however, are equally forbidden to the cleric unless the competent authority grants a license (can. 139).
Zaccaria da S. Mauro