In the late nineteenth century, Catholic moralists argued strongly over the lawfulness of various operations that resulted in the death of a pre-born child but which saved the life of the mother. In the same time period, the Congregation of the Inquisition (the Holy Office) began issuing formal responses to questions concerning specific cases and procedures. While those decisions practically settled matters for the moralists of the time, in the decades following the Second Vatican Council similar debates have arisen among authors desiring to be faithful to the teachings of the Magisterium. Disagreements concern not only the morality of specific operations in difficult situations, but also the principles that specify human action, the definition of terms like "abortion," and the authority and proper interpretation of magisterial interventions themselves.

The purpose of this study is to identify and analyze the teachings of the Magisterium on direct abortion and their interpretation by Catholic moralists from the late nineteenth century to the present in order to inform current debates among Catholic scholars on the understanding and application of those teachings. This dissertation is divided into three principal parts, following periods of development in magisterial teaching: the period of the Holy Office decisions (1884-1902), the period from the first Code of Canon Law to the Second Vatican Council (1917-1962), and the period from the Council to the present. In each section I present the teachings or decisions in their respective contexts, including relevant questions or debates that may have occasioned or resulted from the magisterial interventions.

This dissertation concludes that since the nineteenth century, while there has been no reversal of prior doctrine at any point, there has been a development of magisterial teaching on direct abortion in at least three ways: 1) the meaning of the term "direct" has been clarified, 2) the meaning of "abortion" has broadened to include more actions than it previously had in the usage of the Magisterium, and 3) teaching on the relationship between direct abortion and direct killing became more explicit. I explain the relevance these and other developments have for current debates.