A slight mutilation, in the sense of the term as commonly used, can be any permanent effect of a wound, bruise, or similar cause, from a mere scar to an amputation or other injury whereby any member of the body is rendered unfit for normal action. That the causal wound or injury is trivial in itself, apart from its effect, as in vasectomy, has little or no direct bearing on the morality of the mutilation. It is possible to have a very gross mutilation without extensive wounding. We can blind a man permanently by putting the point of a fine cambric needle one-twentieth of an inch within the pupil.
Vasectomy is a grave mutilation because (1) it removes from the man the power of generation; (2) it inhibits the function of the testicle, which is an important organ of the body. Although they are not the entire organ of generation, the testicles are together a complete organ in themselves, the function of which is to produce the spermatozoa essential to the procreation of the human species. If by a wound one inhibits the function of the testicles, he gravely mutilates the human body, for a grave mutilation is nothing but an inhibition of the function of a distinct organ through a wound.
A mutilation of this kind, since it frustrates the production and action of the human generative semen and prevents generation, is what is technically called a mortal sin against nature, unless there is sufficient cause to necessitate the frustration, such as to save life, to restore as a sole means the health of the whole body, to protect society, or a similar reason. What is said here of vasectomy is true for fallectomy or other methods of sterilizing the woman. Fallectomy, however, is in itself a dangerous operation, and oöphorectomy is never justifiable as a mere method of sterilization because of its very injurious effects on the whole body and mind of the woman.
Among the decretals of Gregory in _Corpus Juris_ (lib. v, tit. xii, c. 5) is the following canon: "If any one, for the sake of indulging lust, or through revenge, does anything to a man or woman, or gives them anything to drink, whereby they cannot generate, or conceive, or bear children, he is to be treated as a homicide." Any one who sterilizes a man by vasectomy or a woman by fallectomy or oöphorectomy, for an improper motive, _ipso facto_ falls under this decree, and is before the canon law classed in the same category as a murderer; that is, the agent is deemed guilty of a grave crime against nature.