There has been much speculation about how much Grotius knew about Asian law and maritime trading customs, and at what stage in his early career he familiarized himself with them. This chapter divides Grotius’ early career (before 1618) into four stages, each corresponding to a phase in his intellectual growth on the subject of Asia at large. First, defending the Santa Catarina incident which saw him drafting De Jure Praedae (and with it implicitly Mare Liberum) before 1606/7; second, defending the VOC’s interests in the lead up to the Treaty of Antwerp and the Twelve Years Truce 1606/7-1609; third, acting as the intermediary for VOC admiral Cornelis Matelieff (Cornelis Corneliszoon Matelieff) 1608-1612/3, and participation in the Anglo-Dutch fisheries and colonies conferences of 1613 (London) and 1615 (The Hague). It is argued that in his various capacities in government and as advisor to the Dutch East India Company (VOC), Grotius broadened his knowledge about Asia in different ways, and through his services to the state and company helped lay the intellectual and foundations for what has been sometimes dubbed the First Dutch Empire (c.1605-1795).

This chapter tracks Grotius’ career as an official serving the province of Holland and the city of Rotterdam up to his arrest in the late summer of 1618. After an introduction on his work as a lawyer in The Hague, his service as advocate-fiscal (public prosecutor) of the Court of Holland (1607-1613) and as pensionary of Rotterdam (1613-1618) is described against the background of the emerging religious conflicts within the Dutch Republic. A special section is devoted to Grotius’ diplomatic activities, especially his membership of a Dutch mission to London in the spring of 1613, where he tried to win king James’ support for the ecclesiastical politics of the States of Holland.

Grotius’ earlier theological controversies concerned the authority of secular rulers and the normative status of the undivided church, principles given fullest exposition in De Imperio Summarum Potestatum. Meletius reveals deeper disagreements with the prevailing Calvinism, insisting on the distinction of core doctrines from theological speculations. The atoning death of Christ, expounded in De Satisfactione Christi, was of central importance to him, and his apologetic interest flowered in De Veritate Christianae Religionis, an exercise in natural theology. The later writings centre on his Bible Commentary and his writings on Christian unity. They reveal some changes upon earlier views, but no accommodation to Catholic doctrinal norms. The polemics with Rivet sharpened his opposition to Calvinism as a dogmatic system with an inadequate conception of the Christian moral life. His status as a layman of no church establishment exposed him to appropriation in support of later agenda that were not his. But his influence was widespread in later Protestantism of many strands.

What is the legacy of Grotius’ doctrinal efforts, and how did they impact on current structures of international law? Was he providing a natural law foundation for the global order, or rather an instrument of power for sovereigns to assert their political and commercial dominion over the world?

Recent studies have observed that in Grotius’ legal doctrine the intellectual ambition to create a universal rule of law (natural law) coexists with a distinctively ‘modern’ use of the vocabulary of individual rights (natural rights). In this chapter, I argue that a more careful reading of Grotius’ engagement with the Aristotelian tradition might cast new light on this traditional dichotomy, and expand our understanding of Grotius’ theory of justice. Famously, Grotius relies on the Aristotelian notion of virtue ethics to introduce the concept of aptitude, which designs a more generic account of merit and moral fitness rather than a strict, enforceable legal claim. Far from being discarded as a ‘minor’ or ‘deficient’ source of right, aptitude plays a fundamental role in this context. Through his reading and translating of the Aristotelian commentator Michael of Ephesus, I will show how Grotius’ thin conception of right as aptitude and fitness provides his natural law doctrine with a heuristic requirement for right reason.

In De jure belli ac pacis, Grotius constructs international law with the vocabulary of private law. For this purpose, he uses distinctions from the Institutes of Justinian and the Digest, but redefines key concepts of Roman law, such as natural law or law of nations (jus gentium). In doing so, he uses a method that is typical for humanist jurisprudence. On the one hand, he describes history, on the other hand, he renews the traditional system of law and adapts the law to the needs of his own day and age.

This chapter examines several elements of Grotius’s teachings on the laws governing promises, contracts, and treaties, as expounded in his De jure belli acpacis. Grotius distinguished between promises and contracts. A promise to transfer a property right is binding when the promisor expressed his intention with an external sign, and the promisee has accepted the promise. As the binding effect is based on the free will of the promisor, the so-called vices of the will (duress, fraud etc.) can invalidate the agreement.

This chapter presents Grotius’ ars politica that deals with what is useful in practice, different from the ars iuris that deals with issues of justice.Philosophically eclectic, descriptive and non-perfectionist, Grotius’ ars politica is directed at understanding and guiding the organisation of power (potestas) and interest (utile) in human live, on two levels: a. the metalevel of theoretical discussion comparing and integrating different approaches to the topic, and b. the practical level of providing answers to political challenges. As agency is central, so is autonomy, and sovereignty.

What is the legacy of Grotius’ doctrinal efforts, and how did they impact on current structures of international law? Was he providing a natural law foundation for the global order, or rather an instrument of power for sovereigns to assert their political and commercial dominion over the world?

Grotius' two major treatises on the law of nations - De jure praedae and De jure belli ac pacis - both had the discussion of the just war doctrine as the backbone to their structure and argument. Whereas the older treatise was construed to argue the justice and legality of the taking of a Portuguese ship in East Indian waters, the more mature work aimed at a systematic exposition of the laws regulating the starting, waging and ending of war. Grotius offered a novel reading of the just war doctrine by rewriting it into the key of his general legal theory and his doctrine of natural rights as subjective rights under commutative justice. This chapter analyses Grotius' reframing o the just war doctrine and his re-systematisation of late-medieval and Renaissance legacies of theologians, canonists and civilians into a new doctrine of jus ad bellum, also giving some attention to its effect for the legal process of peace-making.

The laws of war, as expounded by Grotius, resulted from an interplay of natural law and the voluntary law (or law of nations), which was a customary law based on state practice.Important ways in which the voluntary law departed from natural law were in according equal rights to belligerents in war, without regard to the justices of the respective causes.The predominant principle governing the conduct of war was necessity, which had both a permissive and a restrictive character.Grotius was a firm supporter of moderation in the exercise of the rights of belligerency.This worked particularly to the benefit of civilians and prisoners of war.He insisted that principles of good faith must operate in war, so that perfidious acts were prohibited, though ordinary ruses of war were allowed.The voluntary law, to Grotius, allowed the unlimited taking of property belonging to enemy nationals.Grotius also gave careful attention to modern concerns such as targeted killing.An important contributions was to lay the groundwork for the law of neutrality, setting out rules on the treatment of neutral-owned property in war and on the treatment of enemy-owned property in the custody of neutrals.

The present article examines Grotius’ views on the relationship between church and state. He composed most of the works dealing exclusively with this theme in the years before 1618, but his later work is discussed as well. The historical and intellectual background to Grotius’ views is examined, such as the Dutch religious troubles, toleration, Jewish history and Erastianism. This is followed by Grotius’ general views on church and state as expressed in his works and his views on specific aspects, such as lawgiving, the right of resistance by the church, synods, ecclesiastical hierarchy, divine and natural law. It is concluded that Grotius held that there is only one, indivisible sovereign government, and that this is civil government: all external acts in the public space are subject to the sovereign. Abuse of this absolute power is restricted by the fact that the sovereign has to render account to God. Grotius’ lifelong ideal was that of a state based on these principles, with a Christian public church, where toleration of religious differences was practised.

Contracts must be regulated by equality, which stipulates that the party who has obtained less because of an inequality shall have a right of action. Grotius proposed a broad concept of equality, which concerns various elements: acts preceding the conclusion of a contract, the principal act, and the subject matter of the agreement. Grotius’s teachings on the law of treaties reflect those illustrated for promises and contracts, but also encompass some differences. For example, Grotius does not condemn treaties with unequal terms.

Grotius lived through a time of great upheaval in Europe as well as in his country of birth, the Dutch Republic. The religious, political and constitutional convulsions that struck the Republic destroyed Grotius' career but also, in combination with fundamental changes in the intellectual outlook of early seventeenth-century Europe formed his views of God, nature, society, politics and law. This chapter introduces the extraordinary polymath Grotius was from the perspective of this background and offers a map to the five parts of this volume, and their respective chapters.