In This Article Expand or collapse the "in this article" section Contemporary Catholic Approaches

  • Introduction
  • General Overviews
  • Sovereignty and International Personality of the Holy See
  • The Critical and Central Role of Diplomacy
  • The Law of Treaties and International Relations
  • The Importance of International Organizations and the Role of the Church

International Law Contemporary Catholic Approaches
Robert John Araujo
  • LAST REVIEWED: 25 February 2014
  • LAST MODIFIED: 25 February 2014
  • DOI: 10.1093/obo/9780199796953-0070


One might question why there is a Catholic approach to, and understanding of, public international law. Answers to these related issues must take into account that the Catholic Church has been involved with international law, diplomacy, and international relations for about a millennium and a half. Consequently, the Catholic approach to public international law has deep roots in history and the evolution of universal principles of law grounded in the natural law. The Catholic Church, as a unique sovereign known as the Holy See, relies heavily upon the bodies of customary and positive (i.e., treaty) law that apply to the relations between and among states; moreover, its approach to the law of nations is also influenced by its own law, the Code of Canon Law. The church was a major, early contributor to the foundation of contemporary public international law especially through the works of the 16th-century Dominican Francis de Vitoria (b. 1483–d. 1546) and the 16th-century Jesuit Francis Suárez (b. 1548–d. 1617). Both of these men contributed to the concept of the “just war” theory dealing with jus ad bellum and jus in bello matters. In addition, de Vitoria, by addressing the relationship between the native peoples of the New World, develops a foundation for the concepts contained in Articles 1–4, 12, 13, 15–19, and 29 of the Universal Declaration of Human Rights. The work of each of these clerics was relied upon by Hugo Grotius (b. 1583–d. 1645), who is considered the father of contemporary international law. However, Scott 2008 (cited under Foundation Sources of the Catholic Perspective on Public International Law) considers de Vitoria the “founder of the modern law of nations” (p. iii) and Suárez the “founder of the modern philosophy of law in general and in particular of the law of nations” (p. iii). The Catholic approach to international law has two dimensions: it is a giver and a receiver of the principles of a universal legal regime. This fact explains why the Catholic Church’s own law (Canon 3 in both codifications of 1917 and 1983) relies upon the esteemed principle of pacta sunt servanda (the agreement must be obeyed). As a member of the international order, bilateral and multilateral agreements that have been negotiated and entered into in good faith are principal instruments for maintaining international justice, peace, and security, which are topics of vital concern to Catholic teachings. Although criticism has been mustered concerning certain treaties entered into by the Holy See with particular sovereigns (e.g., the 1933 treaty with Germany), the church is dedicated to the principle that treaties (or concordats, as the church refers to its treaties with other sovereigns) are entered into and observed to ensure that the “rule of law” rather than the “rule of might” prevails in international relations. Today, the Holy See is an active participant with many other sovereigns and with international organizations in making, applying, interpreting, and following principles of public international law. In addition, the Holy See has been asked to lend its expertise and good offices to ensure that other sovereigns rely upon principles of international law rather than the use of force to resolve disputes. A critical element of the Catholic approach to international law is securing and maintaining the common good, which is a vital concept practiced by the church and is founded on the idea that the welfare of the entirety is dependent on the welfare of its elements and the welfare of its elements is dependent on the well-being of the whole.

General Overviews

Two general sources of information touching upon the topics discussed in this article are the Compendium of the Social Doctrine of the Church (Pontifical Council for Justice and Peace 2004) and the four-volume New Catholic Encyclopedia: Supplement 2012–13 (Fastiggi 2013).

  • Fastiggi, Robert L., ed. New Catholic Encyclopedia: Supplement 2012–13; Ethics and Philosophy. Detroit: Gale Cengage Learning, 2013.

    This contemporary four-volume supplement covers in encyclopedic fashion most of the topics addressed in this article by informed scholars. Each entry also includes a bibliography directing readers to additional treatments of the subjects discussed.

  • Pontifical Council for Justice and Peace. Compendium of the Social Doctrine of the Church. Rome: Libreria Editrice Vaticana, 2004.

    This comprehensive text offers a contemporary overview of biblical and official church documents addressing most of the substantive issues contained in this article.

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