ABSTRACT
The law of obligations is one of the most significant contributions of Roman law to legal culture, illuminating the civil law tradition more than any other branch of Roman law. The most usual form of performance of an obligation was by payment. Like ownership or inheritance, obligation was originally an exclusively civil-law concept. Praetorian obligations were established by a praetor's own jurisdiction and were enforceable by praetorian actions, especially actions in factum. Natural obligations could be used to offset a claim of the debtor. Probably based on the Aristotelian distinction between voluntary and involuntary activities, Gaius Caesar in his Institutes introduced a primary division of the sources of obligation. Romans identified and regulated a series of individual delicts in both civil and praetorian law, and they protected the injured person with penal actions. Justinian's compilers subdivided the "various types of causes" Gaius mentioned in Res cottidianae into those that were closer to contracts and those that were closer to delicts.
