Contract of sale is the most important possessory contract which refers to the property transfer of an object of sale from seller to buyer. Third party claim regarding the ownership of an object of sale will undermine the effectiveness of the aforementioned rights. Regulations governing the Iranian law concerning meddle deals and defects warrantor implies that such claim will result in total cancellation of the contract of sale and the status will return to what was previously (i.e prior to conclusion of the agreement). Accordingly, it is essential to secure entire rights of the claim asserted by third party (owner), refund the original property (object of sale) to the party that possess it, and compensate for all the losses. The original buyer, however, can only request the price previously paid, expenses of judicial proceedings and the like, albeit with much less buying power and in case of ignorance that object of sale belonged to someone else. In fact, the current regulations are based on a supportive approach to the benefit of “owner”, so that rights of the original buyer are considered submissive to quality of the rights demanded by the owner; because nullification of the agreement between the dealers will hamper contractual claims of the seller against the buyer. In other words, the buyer can merely pursue the price previously paid and regain the former status. Therefore, the condition of “nullité partielle” of contract in such cases is similarly recognized in the Egyptian law that actually originates from the French version of law, based on which the contractual relationship between buyer and seller is distinguished from their relationship with the owner and its validity remains despite the nullity regarding the owner. Partial nullity (nullité partielle) can promote the supportive approach in benefit of the original bona fide buyer and become more compatible with the principles of justice and fairness.