Seeking to explain democratic right of sovereignty has been of such a historical background as that of human political thought. The theory of joint ownership, refuting divine legality and social contract and as a basis for sovereignty during the age of Imam`s absence, seek to justify right of sovereignty on the basis of religious teachings. Now, on this basis, a question appears in mind as: may joint ownership as a political theory be regarded as the basis of Islamic political system today? The hypothesis is formed as: joint ownership is not taken from practical wisdom and is not founded upon revealed teachings; on the contrary, it is completely based on some teachings taken from common sense. The failure of the theory, therefore, would be made clear with regard to the theory`s difficulties. It is, finally, concluded that considering failure of the theory, not only government in Islam is not refuted but it would be known as necessary also.