One of the most important issues related to constitutional institutions is its independence and impunity from the pressure other branches of government. In this regard, the way in which they are selected, and more specifically, the decision-making bodies on their installation, has direct impact on the quality of their work. The more accurate the selection method, the more precise its criteria, and away from political considerations, the more qualified and more independent people are selected. The relationship between the constituency and the appointment of members has two major patterns. Single entity pattern and mixed entity pattern. One of the branches of the second model is the model of parliamentary sovereignty. This model has an important role for parliament in that it elects and approves the final members of the body that assists parliament. Iran has selected half of the members of the Guardian Council to work to determine the extent of its independence. The lack of clarity in the constitution regarding the participation of the judiciary and parliament in the selection of jurists and the interpretation of the Guardian Council's interpretation of limiting parliament's interference with the prediction of the relative majority vote and the gap between the judiciary and the Bar Association and the academic community are problems. It is far from the criteria of the parliamentary majority model.