Article IV. On Unnatural Intercourse with a Person of Diverse Sex

I. Notion. Unnatural intercourse is here understood as intercourse of a man with a woman in the posterior vessel or - as others add - in the mouth. Namely, the malice of this sin consists in mingling with a person with whom someone can procreate offspring, but with whom he is here and now mingled in such a way that offspring cannot be procreated. It is said in mingling; hence congress in a vessel is required. It is said with whom he is so mingled that offspring cannot be procreated; hence congress in an undue vessel is required, that is, in the anus. There is dispute about congress in the mouth, which according to some is pollution, to which an affection toward fornication is added; but according to others it is equated with coitus with a woman in the posterior vessel, because here likewise there seems to be mingling with a person of diverse sex (St. Alphonsus VI, 935).¹ Intercourse with a woman in the posterior vessel is more often called sodomy improperly so called or imperfect; intercourse in the mouth is called irrumatio. Moreover, imperfect sodomy and irrumatio do not differ in species, because the malice of each consists in mingling with a person of diverse sex in an undue vessel.

Note. Intercourse in another part of the body - besides the posterior vessel and the mouth - is pollution with an affection toward fornication; it does not matter in what part it takes place.

¹ Cf. however St. Alphonsus III, 466 and Homo Apostolicus, tr. 9, n. 25.

II. Morality. 1. The unnatural intercourse of which we are speaking - equally and for the same reasons as pollution, sodomy, and bestiality - is intrinsically and gravely evil.

The Sacred Penitentiary responded on April 3, 1916: "If the husband wishes to commit with her the crime of the Sodomites, since this Sodomitic coitus is an act against nature on the part of both spouses thus coming together, and by the judgment of all doctors is gravely evil: hence for absolutely no cause, not even for avoiding death, can the wife licitly comply in this matter with her immodest husband. And the Sacred Penitentiary vehemently marvels that the opposite opinion, with disgrace to human nature, could have persisted in the minds of certain priests, as is reported."

2. The sins of the agent and of the patient do not differ in species. The circumstance of seminal emission, however, if it has taken place, must be made known, and therefore the things set forth under n. 53, 2, are to be observed.

3. Unnatural intercourse perpetrated with a blood-relative or affine, equally as direct intercourse had with them, takes on the malice of incest; likewise of adultery, if it is perpetrated with a married woman.

Note. Inquiry should not be made into unnatural intercourse with a person of diverse sex; for if the penitent is silent about it, it is presumed not to have taken place. Besides, if intercourse was had outside the anus and mouth, the penitent should not be asked in what part of the body it occurred, because, as we have noted, that matter is irrelevant.