A Study of Natural Obligations in Law of Iran with an Approach of Legal and Economic Analysis

Natural obligations is one of various kinds of obligations that there are diferent viewpoints on its basis and nature. these are obligations in which, the obligee has no claim right but if the obligor voluntarily fulfilled the obligation, his/her claim for restitution will not be admissible. the question here is: what is the legal nature of natural obligation? what are its instances? And which legal rule) from economic principles) is more efficient and desirable about such obligations? Using the jurisprudence juridical and economic principles, can said that, prohibition of unlawful possession or prohibition of unlawful utilization of a property is the best legal establishment that illustrates basis and nature of natural obligations. Moreover, time lapse debts, leniency contracts debts, denied by oath, debts related to credibility of judgment and kinfolks (relatives) past alimony can be counted as instances of natural obligations. Also observing social costs, provisions of article 266 of civil code on inadmissibility of claim for restitution of debtor who has paid the real debt, as a legal source in natural obligations is efficient