1. History and Philosophy
1 The Latin term bona fides, often also used in the inflected forms bonae fidei and bona fide, means good faith. The very wording already discloses a broad intent because of which the bona fides principle—even though being fundamental to more or less every legal system on a world scale—has often been criticized as ambiguous if not amorphous or elusive. However, limiting bona fides to a vague moral dimension or to its self-evident spirit of reasonableness would fall short of comprehending the principle’s historically and philosophically diversified content (see also Ethos, Ethics, and Morality in International Relations; Reasonableness in International Law).
2 As early as 1659, good faith was mentioned in an international peace treaty: the Treaty between France and Spain ([signed 7 November 1659] [1659] 5 CTS 325), signed to end the Franco-Spanish War that had begun in 1635. Before that, in 1625, Grotius had referred to the Aristotelian parameter that if ‘good faith has been taken away, “all intercourse among men ceases to exist”’ (De Jure Belli ac Pacis Libri Tres Book III Chapter 25, 1). Grotius also referred to Cicero’s famous observation according to which ‘in good faith what you meant, not what you said, is to be considered’ (Book II Chapter 16, 1, 1). For Isocrates the good faith principle was common law of all mankind. Aristotle’s philosophy of the good and fair, of equality and justice, especially his Nicomachean Ethics, clearly describes all social intercourse as being based upon the requirement of good faith. Since its Greek—and even earlier—origins, good faith is an expression of ius aequum rather than ius strictum. As an intrinsic requirement of justice, bona fides-thinking is strictly opposed to mere legal formalism over-emphasizing the written law and formal structures instead of keeping the very ideal of a just legal order in mind.
3 The concept of good faith has been a key element of ancient Roman law, in particular contract law but also public law (fides publica). Originally, bona fides contracts were to be distinguished from stricti iuris, that is to say formal, contracts. Bona fides was conceived as a material source of law from which new rules could be derived. Closely related to the divine sphere, breaching good faith also meant acting against the will of the gods and sacred obligations stemming therefrom. More rationally, Cicero qualified good faith as a foundation of justice, and the principle was held to be an indispensable prerequisite for trustworthy, honorable, and conscientious conduct. Consequently, good faith worked as the principle to bind a foreigner and a Roman citizen to their agreement (pactum nudum). Governing the performance of contracts, bona fides outlived the Imperium Romanum and appeared again in early medieval mercantile law and practice. For Bynkershoek, consent-based public international law would have been impossible without its bona fides foundation: ‘Pacta privatorum tuetur Jus Civile, pacta Principium bona fides’ (Bynkershoek 251; ‘Agreements between private parties are governed by civil law, agreements between sovereigns by bona fide’ [translation by the author]). Throughout both civil and common law regimes, good faith gained high validity as a ‘governing principle … applicable to all contracts and dealings’ (Lord Mansfield in Carter v Boehm (1766) 3 Burr 1905, 97 ER 1162 at 1164).
4 Furthermore, the notion of bona fides being an indispensable means to attain fair and just results is deeply rooted in Christian as well as secular natural law doctrine (Natural Law and Justice). Early modern classics of public international law, including Grotius, Suárez, de Vattel, Pufendorf, or Wolff, are among the most important representatives of this natural law concept. Nature was closely linked to reason. Particularly in the age of enlightenment, the strong trust in human reason became what one could describe as an epoch-making paradigm. Good faith and, to some extent as a prerequisite, to some extent a consequence thereof, pacta sunt servanda were to create a spirit of respect for the legal order and hence legal, political, and economical stability as progress for all mankind (Kolb (2000) 86–92). Thus conceived, good faith formed an obligation of any nation to take into account the reasonable expectations of all other members of the international community. This led to a rule of reason-based method of treaty interpretation long before the Vienna Convention on the Law of Treaties (1969) (‘VCLT’) excluded unjust—or at least unjustified—outcomes of a strictly literal interpretation. In this natural law tradition, John Rawls’ philosophy of justice as fairness, comprising procedural as well as substantive elements, relies not only on general principles of justice, but also on reason. In post-modern legal theory, however, ‘reasonableness’ is challenged by diverse ‘critical legal studies’ approaches (International Legal Theory and Doctrine).
2. Law Comparison
5 Good faith belongs to the very few legal principles which do find resemblance in more or less all legal systems and legal cultures. It might very well be characterized as an anthropological proposition of contractual legal conduct. In Europe, good faith is a central area for the contract law of all European Union (‘EU’) Member States. Examples stemming from the French civil law tradition can be found, for example, in the Code civil (French Civil Code; in particular Art. 1134, furthermore Arts 201-02, 220, 491-2, 510-3, 549-50, 555, 1378, 2265, 2269), in the Code de la sécurité sociale (R243-20 al. 3) or in the Code de commerce (French Commercial Code; Arts L225-102-1, L235-12, L622-3, L670-1). For Germany, Art. 242 Bürgerliches Gesetzbuch (German Civil Code) has to be mentioned. Beyond the EU, for example, Art. 5 (3) Constitution of the Swiss Confederation provides for an innovative clause binding private as well as public actors to the principle of bona fides: ‘State and private organs must act in accord with good faith’. Russian civil law also emphasizes bona fides-obligations.
6 Moreover, common law countries rely on the notion of good faith. Regarding the United States of America and their attempt to unify common law rules in statutory provisions, the Uniform Commercial Code (‘UCC’) gives an example. Art. 1-201 (20) UCC states: ‘“Good faith” … means honesty in fact and the observance of reasonable commercial standards of fair dealing’, while Art. 2-103 UCC, applicable to merchant sales in transaction, more specifically speaks of ‘honesty in fact and the observance of reasonable commercial standards of fair dealing in the trade’. Deeply rooted in Chinese cultural traditions, especially in Confucianism, the principle of chengshi xinyong is an expression of honesty and trustworthiness forming an equivalent of the English good faith (Cao 167). Finally, in the context of Islamic legal cultures, Art. 246 Civil Code of the United Arab Emirates can be seen as another indication of the universal nature of bona fides (see also Islamic Approach to International Law).