(1) Unilateral and bilateral (unilate-rales and bilaterales). This distinction is based, not upon the way in which the contract is formed, since in this respect there is no contract that is not bilateral, but upon its effect. If only one obligation springs from it, it is unilateral. According to the old Roman law, an obligation is in form unilateral when one party is creditor and the other debtor, so that by only one of them can a suit be maintained {actio directa), the other party being limited to set-off, or actio contraria. A bilateral contract, therefore, is in this view the fusion of two obligations, the performance of the one being conditioned on the performance of the other. Each party can on such a contract sue the other in an actio directa.

(2) Onerous and lucrative. A lucrative contract is one which brings pecuniary benefit to one party alone. An onerous contract is one in which each party gains something and parts with something. Onerous contracts are, therefore, in the main, convertible with bilateral. But lucrative contracts are not convertible with unilateral, since there are unilateral conr tracts which are not necessarily lucrative.

' Koch, Ford. sec 69.

(3) Conventiones juris civilis and juris gentium. "Pactio aut legitime aut juris gentium," L. 5, pr. D. de pact. (2-14). This division relates to the system of law on which the contract rests, and to which recourse must be made for its enforcement. In the same way we may speak of contracts good in law, and contracts good in equity; and of contracts for which distinctive statutory remedies are provided (e. g., deeds duly acknowledged and recorded), and contracts for which there is no distinctive statutory remedy.

(4) In bonce fidei and stricti juris contractus. This is a processual distinction. Contracts ex jure gentium are not necessarily bonœ fidei contractus.

Koch's second division is as follaws :