Giovanni Maria Lampredi studied grammar, literature and Latin at the Eugenian Seminary in Florence, where he also obtained his degree in canon law and theology. In 1756, he was ordained priest. His early career and writings focussed on Etruscan society, culture, politics and history (Saggio sopra la filosofia degli antichi Etruschi, Florence 1756; Governo civile degli antichi toscani e delle cause della lor decadenza, Lucca 1760). From 1760, he began to study natural law and public law, in which period he published De licentia in hostem and De maiestate (Florence 1761). In 1763, he became professor of canon law at the faculty of law in the University of Pisa. Three years later he took up the chair in public law which he held until 1792.

As a professor, he dedicated most of his time to teaching and publishing works on natural law, public law and law of nations, such as Iuris publici universalis, sive Iuris naturae et gentium theoremata (Livorno 1766-1768). These works, together with Del commercio dei popoli neutrali in tempo di guerra (Florence 1788), are considered his major contributions. The latter publication also won international visibility which brought him closer to the Grand Duke of Tuscany, Ferdinand III, who gave him a key role in his admnistration Lampredi intervened against the frumentary laws of Ferdinand’s predecessor, Pietro Leopoldo (1792). Ferdinand moreover commissioned Lampredi to work on codifying the laws of the Grand Duchy, but the task was not completed due to Lampredi’s death in 1793 of apoplexy and severe dropsy. Among his numerous students were Francesco Foggi (1748-1824) and Giovanni Carmignani (1768-1847), whose works on criminal law were influenced by Lampredi’s thinking.

In De licentia in hostem Lampredi analysed the legal limits of the use of violence in starting a war (ius ad bellum) and also in conducting one (ius in bello). He criticised the theory of infinita licentia in hostem and distanced himself from Samuel von Koch’s (Cocceius) theories of the unlimited freedom of the combatants. For Lampredi, war had to be conceived only as an extrema ratio, and the only ‘just’ war was the one waged solely in defence of the natural rights of states. In De maiestate principis, Lampredi used Barbeyrac’s and Pufendorf’s works as source in order to support the concept of law as a sanctioned command and as an expression of the will of a superior authority, which also possessed the power to punish. Lampredi supported Pufendorf and Koch’s position that God is the legislator of natural law: the natural society is characterised from equity and freedom and the natural obligation “idem sane dici nequit ac simplex poenarum timor” (De Maiestate, p. 88).

Iuris publici universalis, sive Iuris naturae et gentium theoremata was conceived, as Paolo Comanducci pointed out, as a textbook for students (Comanducci 2012, p. 1139). It was modelled on German textbooks on natural law and law of nations published between the 16th and 17th centuries. Lampredi structured this work in three parts: In the first part, he considered theoretical ethics and natural law, arguing for the centrality of reason for understanding human nature. The second part was dedicated to public law, where he analysed the origin of the civil society and the social contract. The central topic of the third part was the law of nations. The law of nations is the natural law applied to all nations. Central in his theories is the role played by trade in the international relations. Trade in fact is conceived as a fundamental tool in order to full fill a natural obligation. This means that the limitation to internal trade constitute a violation of natural law; where the limitation to external trade could be imposed under specific conditions, as for example the overabundance of goods. In Del commercio dei popoli neutrali in tempo di guerra he fervently supported freedom of trade between neutral states, based on the law of nations and of treaty law. This was a response to the theses advanced by Ferdinando Galiani’s De’ doveri e de’ principi neutrali verso i guerreggianti e di questi verso i principi neutrali (Naples 1782).

Del commercio dei popoli neutrali in tempo di guerra could be seen as a sort of synthesis of Lampredi’s positions on the law of nations. It examines in detail both the principles that regulate trade between neutral states and also the most significant doctrinal positions taken in this matter throughout history. In addition, it contains a collection of treatises of maritime law of neutrality. The peculiarity of Lampredi’s work lies not only in his theoretical arguments but also in his constant attention to practice and to the historical and political situation of the Grand Duchy of Tuscany, whose commercial interests on the European stage he tried to protect and defend legally. Lampredi’s approach was attentive to the legal impact of trade and economic relations between States, with the aim to regulate these according to the law of nations.

Lampredi’s natural law system tried to bring together Pufendorf’s imperativism and Wolff’s rationalism, even if he supported Wolff’s approach in the end. He also recognised the search for happiness within the theorem of natural law. He argued that natural law served as a criterion of evaluation in order to examine human law according to universal justice. Natural law should serve as a sort of tool to interpret the ius commune system and also to support and advise the sovereign. At the same time he considered natural law, together with public law and law of nations, as a ‘key subject’ with the specific function of giving students uniform and coherent universal principles through which they could interpret existing laws and create new ones.