A Catholic vasectomy is supposedly a male sterilization procedure that is sanctioned by the Catholic Church, but it does not really exist. In a vasectomy, a man’s vas deferens is cut and cauterized to prevent sperm from being ejaculated during sexual intercourse. If a man’s life is in danger, however, he may seek out a procedure that could render him sterile, and some people refer to this as a Catholic vasectomy because it is believed to be condoned by the church.
With the advent of technologies to better control human fertility — like prophylactic barrier methods, such as condoms and vaginal sponges; surgical procedures, like tubal ligations and vasectomies; and the birth control pill — the Catholic Church had to re-evaluate its stance on procreation. The church’s stance had always tended to be one that emphasized sexual intercourse as solely a means for procreation. In 1968, Pope Paul VI issued an encyclical called Humanae Vitae or “On the Regulation of Birth”.
An encyclical is a letter issued by the papacy, for wide circulation, that deals with a particular issue. This one dealt with conjugal issues between married partners. It also detailed when it is acceptable to use birth control or undergo what some call a Catholic vasectomy.
The encyclical states that partners should exercise responsible parenthood, and are encouraged to practice natural family planning. This uses the rhythm method and fertility awareness as means for controlling when a couple conceives a child. In the rhythm method, the couple abstains from intercourse when it is believed that the woman is at her most fertile, based on when she last menstruated. The fertility awareness method actually tracks the woman’s basal body temperature to more accurately predict when it is not safe, in terms of birth control, to have intercourse.
While the encyclical does affirm that sex between married partners is a beautiful expression of their love for each other, that can be had without the intent of procreation, it explicitly declares it to be unacceptable to interrupt natural fertility. In other words, it goes against God's design to interfere with conception by using chemicals, condoms, or surgical procedures. If a man gets a vasectomy and goes against this design, then it is believed to be a mortal sin. A mortal sin is an act that, unless it is absolved, the perpetrator will be consigned to Hell in the afterlife.
The Catholic Church does make allowances for birth control and sterilization for life-threatening conditions, and this is where the idea of a Catholic vasectomy comes from. For example, a man cannot have his testicles removed or have his vas deferens severed unless he has a medical condition, like cancer, that directly threatens his life. The chances of having what some call a Catholic vasectomy are very small. If a man has had the procedure in the past, but wishes to be active within the church, it is recommended that he seek to have the procedure reversed. In such cases, he may also be advised to get counseling from his priest.