The principle of double effect is often used in bioethics as a tool to evaluate significant cases in obstetrics and gynecology. In this article the author, a Catholic priest, presents and interprets St. Thomas Aquinas’s delineation of the principle and discusses several classical applications, namely, to hysterectomy during pregnancy, ectopic pregnancy, and craniotomy. He explains the medical anatomy and physiology of the conjoined Maltese twins, Jodie and Mary, and then examines the arguments of four moralists on their separation. He concludes by arguing that the principle morally justified the surgical separation of Jodie and Mary. National Catholic Bioethics Quarterly 9.1 (Spring 2009): 85–96.

Is it ethical to perform a surgery whose purpose is to make a male look like a female or a female to appear male? Is it medically appropriate? Sexual reassignment surgery (SRS) violates basic medical and ethical principles and is therefore not ethically or medically appropriate. (1) SRS mutilates a healthy, non-diseased body. To perform surgery on a healthy body involves unnecessary risks; therefore, SRS violates the principle primum non nocere, “first, do no harm.” (2) Candidates for SRS may believe that they are trapped in the bodies of the wrong sex and therefore desire or, more accurately, demand SRS; however, this belief is generated by a disordered perception of self. Such a fixed, irrational belief is appropriately described as a delusion. SRS, therefore, is a “category mistake”—it offers a surgical solution for psychological problems such as a failure to accept the goodness of one’s masculinity or femininity, lack of secure attachment relationships in childhood with same-sex peers or a parent, self-rejection, untreated gender identity disorder, addiction to masturbation and fantasy, poor body image, excessive anger, and severe psychopathology in a parent. (3) SRS does not accomplish what it claims to accomplish. It does not change a person’s sex; therefore, it provides no true benefit. (4) SRS is a “permanent,” effectively unchangeable, and often unsatisfying surgical attempt to change what may be only a temporary (i.e., psychotherapeutically changeable) psychological/psychiatric condition. National Catholic Bioethics Quarterly 9.1 (Spring2009): 97–125.