Freedom of the Subject-matter of the Contract

One of the requirements mentioned in Islamic jurisprudence for the subject-matter of the contract is its being free from other’s rights، and in view of this requirement، sale of such things as pledge and vaqf (property that is religious endowment) is forbidden. There is disagreement whether this requirement is an independent term or is deduced from preclusion of such sales. Iranian civil Code does not mentioned the requirement but some of its instances could be found in its sections as well as in other Acts. This article tries to show that freedom of the subject-matter of the contract is a general requirement for all contracts and failure to comply with it could result in the invalidity of contract.