According to Common Law Rules of England, obligation by one party is enforceable when the other has provided a consideration or the contract has been put in a deed. In some common law jurisdictions, such as Australia, Canada and the United States, another doctrine, named Reasonable RELIANCE, has developed, which could act as surrogate for the doctrine of consideration. English courts, however, have not been prepared to accept such function for this doctrine. According to the doctrine, act of one party when it has been relied by the other, may give rise to an obligation on the first party. This doctrine has been criticized in Common Law countries and may be criticized from the Iranian law viewpoint. However, it has many points in common with some rules in Islamic jurisprudence and Iranian law, and review of this doctrine could prepare a suitable ground for the comparison between Common Law and Islamic jurisprudence and Iranian law in a small part of the law of obligations.