Imamiyah jurists and Iranian legal experts have divided contracts into valid and invalid in terms of their effect and often, classified the unauthorized contract under the valid contracts.Comparative studies in recent years have led to the emergence of a new circumstance as voidable contracts in Iranian law.These contracts are considered to be valid and operated by the parties but they are voidable due to reasons such as mistake, duress or operation.Referring to some articles of the Commercial Code and Sea Act, the legal Peeler experts though consider the relative refutation to be in contradiction with the general rules of contracts, have still accepted them as a necessary and new establishment in specific cases.The authors, studying the reasons of the relative nullity in common law and comparing it with similar cases in Iranian law through a descriptive-analytic method, have concluded that there is no necessity for discussion of the voidable contracts in Iranian law, common law and Roman-German law and contrary to what is taken certain, the claimed extensions are in line with the general rules of the contracts related to the unauthorized Swim Top contracts and are justified.