The topic of coniugium leprosorum in the thought of theologians and canonists, from the Middle Ages through the Early Modern Period, is articulated into a variety of relevant issues. Besides its effects on sponsalia, the serious disease casts doubt on the validity of the marriage and, between theory and practice, on how to deal with spouses in case of lepra superveniens. Furthermore, the disease involves the so-called carnale debitum. In the presence of a serious disease, what are the limits of jus in corpus? Is it allowed the fulfilment of the obligation at the expense of one’s own life and for the benefit of (spiritual) health of someone else, or ad bonum commune? How to consider the behaviour of one who denies sexual performance for fear of procreating offspring afflicted with severe anomaly? Consequently, can be life considered a damage to the child? This essay deals with reasoning that, in a prolific dialogue between morality and law, were used to reach solutions to questions that look close to our postmodern bioethical and legal dilemmas.