Sources and Classifications of Obligations

An obligation derived its specific features from the action in terms of which it was enforced and, in particular, from the relevant procedural formula from which the content or legal cause (causa) of the obligation could be inferred.

Gaius, in his Institutes, states that obligations fell into two principal categories: obligations arising from contract (obligationes ex contractu), and obligations aris­ing from delict (obligationes ex delicto).^[574] The term contractus was understood to denote any lawful juristic act capable of producing rights and obligations, and enforceable by means of an action at law. As the vast majority of lawful juristic acts creating obligations were transacted because there was agreement on the part of the parties to establish an obligation, it was in time recognized that agreement (consen­sus) was the essence of a contract. The delictum was an unlawful act (also referred to as maleficium) that was detrimental to the lawful rights and interests of another person and which generated an obligation between such person and the malefactor. The content of such obligation was directed at satisfaction, compensation or a penalty (poena). Gaius' original dichotomy of the sources of obligations was subsequently deemed unsatisfactory, since an obligation could also arise from a legal act with respect to which there was no agreement on the part of the parties concerned. Accordingly, a third category of obligations (also attributed to Gaius) appears in the Digest: obligations arising from various causes (obligationes ex variis causarum figuris) other than from contract or delict.^[575] The phrase variae causarum figurae refers to juristic acts that were not based on agreement, yet were deemed wholly lawful.

Gaius' final classification was probably the precursor of the fourfold division of the sources of obligations adopted by the compilers of Justinian's Institutes.

A further classification of obligations, recognized from an early period, was that between obligationes civiles and obligationes honorariae or praetoriae. The former derived their authority from the ius civile and could be enforced by means of actiones civiles, i.e. actions originating from the civil law. The obligationes honorariae, on the other hand, arose from the ius honorarium and were enforceable by means of actiones honorariae, i.e. actions created by the praetor and other jurisdictional magistrates.^[578] In this connection reference may also be made to the distinction between obligations of the strict law (obligationes stricti iuris) and obligations based on good faith (obligationes bonae fidei). An obligatio stricti iuris arose from a legal act of the strict and formal ius civile. An obligation of this kind was enforced by means of an actio civilis and in such a case the judge was bound by the strict letter of the law. An obligatio bonae fidei, by contrast, derived from a legal act based on good faith (bona fides) and was enforced by an actio bonae fidei, i.e. an action whose procedural formula required the judge to take the requirements of equity and good faith into consideration.

Finally, a distinction was drawn between obligatio civilis in a wider sense and ‘natural obligation' (obligatio naturalis).

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