According to the Article 85 of the Constitution of the Islamic Republic of Iran, legislative and experimental legislation is a type of law-making that is an exception to the principle of “ prohibition of delegation of legislative authority” . Although such laws are accepted in the Iranian legal system and have advantages such as speed in legislation, reducing inflation and increasing the efficiency of laws, but confronts with objections like contradiction with the principle of prohibition of delegation of authority, the principle of separation of powers, the characteristics of collectiveness and transparency of the parliament. Despite the exceptional nature of this type of legislation, in many cases, it has been treated as a principle and this has resulted in violation of the principle of prohibition of delegation. Also, since in practice, a precise assessment is not made after the end of the probationary period, as a matter of necessity and in accordance with the Article 85 of the Constitution, if a precise assessment is made after the end of the probationary period, it is acceptable as a desirable law. This research is done through a descriptive-analytical method based on the documentary data, but is also an applicable research because its results change the existing procedure.