The Principle
Hugo Grotius's De Jure Belli ac Pacis (On the Law of War and Peace, 1625) is the founding text of modern international law and one of the most extensively Scripture-saturated legal works ever written. Grotius drew on hundreds of biblical citations alongside classical sources to argue that the laws governing warfare and relations between nations derive from natural law implanted by God in human reason - and that this natural law could be demonstrated from both reason and Scripture. His work made the Bible a primary authority for international legal obligation at the very moment when the modern nation-state system was emerging from the ruins of the Thirty Years' War.
Biblical Foundation
Grotius saturated De Jure Belli ac Pacis with scriptural argument. Deuteronomy 20:10 - "When thou comest nigh unto a city to fight against it, then proclaim peace unto it" - grounded his insistence that war must be preceded by a formal declaration and offer of terms. Matthew 5:9 - "Blessed are the peacemakers: for they shall be called the children of God" - framed the entire work's orientation toward peace as the ultimate goal of the law of nations. Romans 13:4 - "for he is the minister of God to thee for good... he beareth not the sword in vain" - grounded his argument for the legitimacy of state-sanctioned warfare within moral limits. Genesis 9:6 - "Whoso sheddeth man's blood, by man shall his blood be shed" - provided the biblical warrant for the principle that unjust killing demands punishment, grounding his theory of just war. Psalms 89:34 - "My covenant will I not break" - supported his argument for the binding force of international treaties. Romans 2:14-15 - the law written on the heart - was Grotius's primary warrant for the claim that natural law is universally accessible without Christian revelation, enabling him to argue that international law binds all nations including non-Christian ones.
Historical Transmission
Grotius wrote De Jure Belli ac Pacis in exile in Paris, drawing on a lifetime of scholarship in theology, classical literature, and law. His work synthesised the Scholastic just war tradition (Augustine, Aquinas, Vitoria, Suárez) with the emerging natural law jurisprudence of Protestant Europe. His famous declaration that natural law would obtain even if God did not exist (etiamsi daremus Deum non esse) was not an attack on religion but a methodological move: he sought to ground international law in principles accessible to all rational persons, including those who disputed theological premises. The Peace of Westphalia (1648), which ended the Thirty Years' War and established the modern nation-state system, was negotiated in an intellectual environment shaped by Grotius's framework. Subsequent international law theorists - Pufendorf, Vattel, Wolff - all worked within the Grotian tradition, developing his synthesis of biblical and natural law foundations for international obligation.
Modern Application
The Hague Conventions (1899, 1907), the Geneva Conventions (1929, 1949), the United Nations Charter (1945), and the Rome Statute of the International Criminal Court (1998) all embody principles whose genealogy runs through Grotius to the biblical sources he cited. The requirement of a just cause for war, proportionality in the conduct of hostilities, the protection of non-combatants, the binding force of treaties, and the accountability of individuals for war crimes are all articulated in De Jure Belli ac Pacis in terms that drew explicitly on Deuteronomy, the Psalms, the Gospels, and Paul. Contemporary just war theory - as developed by Michael Walzer, James Turner Johnson, and others - remains in direct conversation with the Grotian tradition and, through it, with the biblical legal texts that Grotius made foundational.
Scholarly Debate
Scholars debate whether Grotius's biblical citations were genuinely constitutive of his legal argument or merely rhetorical decoration for conclusions reached by natural reason. Richard Tuck's Natural Rights Theories argues that Grotius's real contribution was the secularisation of natural law, with Scripture providing illustrative rather than foundational authority. Contra this, Harm-Jan van Dam and others have argued that Grotius's theological formation - he was a committed Arminian Christian and biblical commentator - made his scriptural engagements substantive rather than ornamental. Peter Haggenmacher's Grotius et la doctrine de la guerre juste provides the most comprehensive analysis of Grotius's sources, demonstrating how extensively he engaged the Scholastic tradition derived from Augustine and Aquinas. For the purposes of understanding the Bible's legal legacy, the most important point is that the founding text of modern international law was explicitly and extensively grounded in scriptural argument - a fact whose implications for the theological roots of international legal order have never been fully reckoned with.