Vitoria's successor as the pre-eminent Spanish explicator of international law, Francisco Suarez, wrote after the Peace of Augsburg and therefore dealt with the reality of an international society and its law. Though he was scarcely sympathetic to this development, we can learn a good deal from his commentary about what his contemporaries regarded as the content of this law.
Suarez was born a Spanish aristocrat and became, like Vitoria, a professor of theology. In 1596, after the Spanish conquest of Portugal, Philip II arranged for the appointment of Suarez to the chair of theology at the Portuguese University of Coimbra. Unlike Vitoria in many respects, Suarez was a Jesuit, a prolific writer whose works in a nineteenth century edition fill twenty-eight volumes, and an aggressive polemicist. A great many biographies have been devoted to him, and his renown does not rest on his contributions to international law.*
His most famous work is the Defense of the Faith against the Errors of the Anglican Sect (1613), commissioned by Pope Paul V. In the course of arguing that the pope possesses powers that include the right to put a heretic king to death in order to protect the Catholic faith, Suarez offered a novel argument: because political power arises from the sociability of man and therefore resides originally in the people, it must be delegated to the prince by “human law”; if the prince turns out to be a tyrant, the pope may assert the rights of the people. Because the source of the pope's power is divine and does not come from the people, this theory gives papal authority a certain supremacy over lay rulers.
It is interesting to note that it is just this move, this particular argument, that constitutes Suarez's principal contribution to international law. He is the first writer to show clearly the ambiguity in the term ius gentium, an ambiguity that often bedevils the first-year student of international law who must confront Article 38 of the statute setting up the jurisdiction of the International Court of Justice, which provides in part that the court will apply general principles of law common to all states. This could reasonably be taken to mean either the universal principles of international law, which must necessarily be common to all states, or principles of domestic law that states happen to have in common (it is the latter).
Suarez saw that ius gentium might be given either of two meanings: in one sense it is the law that all peoples and nations (populi et gentes) observe in their mutual relations (inter se); in another sense, it is the law that various states (civitates vel regna) observe within themselves (intra se). The first concept is, for Suarez, the proper ius gentium, and this distinction, so important for the development of international law, also supports the international application of Suarez's deprecation of the power of princes within the princely state. (Note that the Peace of Augsburg, which was otherwise so offensive to the Catholic Church because it replaced the medieval paradigm of a single European polity, was nevertheless crucial to Suarez's argument: Augsburg's recognition of the status of the princely state allowed Suarez to distinguish between the power held by the prince in trust to the State, and his dynastic, personal power.)
In his most famous passage—and one frequently characterized as a hymn to international law22—Suarez sets out his view that the origin of international law lies in the society of states. If we read this passage carefully, however, and bear in mind his arguments in The Defense of the Faith, a somewhat less admiring view of the post-Augsburg world emerges than might at first appear.
The human race, though divided into different nations and states, still has a certain unity, not only as a species but, as it were, politically and morally as is indicated by the precept of mutual love and charity which extends to all, even to strangers of any nation whatsoever. Therefore, though each perfect polity, republic or kingdom is in itself a perfect community, consisting of its members, nevertheless each of these communities, inasmuch as it is related to the human race, is in a sense also a member of this universal society. Never, indeed, are these communities, singly, so self-sufficient unto themselves as not to need a certain mutual aid and association and communication, sometimes for their welfare and advantage, sometimes because of a moral necessity or indigence, as experience shows. For this reason they need a law by which they are guided and rightly ordered in respect to communication and association. To a great extent this is done by natural reason but not so sufficiently and directly everywhere. Hence, special rules could be established by the customs of these nations.23
Rather than exalting a new “world made of law,” in fact Suarez is eager to explain how natural law can account for legal events like the Peace of Augsburg, and the various practices of states that flow from their formal relationships. This enables him to demote, not exalt, the ius gentium (international law) as a mere supplement to natural law. The only treaties Suarez discusses are peace treaties: the observance of these he attributes to the law of nature because they (unlike the rest of international law) are the consti-tutional source of the law among states. Whether or not treaties are to be entered into in the first place Suarez carefully makes a mere matter of the ius gentium. By this characterization he ascribes the actions of the society of states to mere human law, and thus renders those actions susceptible to a superior theological judgment.
Thus so much of what is hailed in Suarez—and we must remember that his work in international law is a small part of the corpus of his writing—is truly important, but not quite in the way it is anachronistically praised.24 Suarez's commentary reflects the dramatic change in European public affairs, not out of sympathy, however, but rather in an effort to contain and limit the significance of what has occurred.
This can be seen in Suarez's attitude toward what we would call today humanitarian intervention—the right of one state to use force to relieve the suffering inflicted on a people by its own state. Suarez clearly apprehends the new community of princely states and does not pretend that the medieval order of a single political jurisdiction still persists. Accordingly he writes that the “assertion made by some writers that sovereign kings have the power of avenging injuries done in any part of the world is entirely false, and throws into confusion all the orderly distinction of jurisdiction.”25 There is one situation, however, that does permit the prince to wage war without the pretext of an injury to his interests or an invitation from the state concerned and that is when “a state worshipping the one God inclines toward idolatry through the wickedness of its prince.” In this we hear the spirit of the Counter-Reformation, of which Suarez was a notable leader, and which was to provoke the Dutch revolt that marked a decisive movement away from the princely state and toward the kingly state. This revolt gave rise to the interpretive work of Ayala.