Expediency is a component that is widely used in different aspects of human life, so there is no doubt about its importance, but its place in different areas of life should be clearly explained. In this research, the information obtained from library sources is discussed with descriptive-analytical method to the place of expediency. Each of the fields of deriving Sharia rulings, enactment of laws and implementation have different characteristics from each other, which leads to an independent examination of the expediency position in each of them. Expediency in the field of inference is as a criterion for falsifying divine decrees in such a way that each division of Sharia rulings has some kind of connection with expediency as a criterion for falsifying rulings. In the field of legislation, laws that have a jurisprudential value in Sharia rulings, expediency in the same sense will be the criterion of falsification, but in laws without a jurisprudential value, as the subject of provincial rulings and the discretion of the Islamic ruler in enacting the laws, it is required in accordance with the requirements of time and place. The position of expediency in the field of implementation is also in two approaches: a) implementation of expediency as a "requirement belonging to a Shariah ruling or law" and b) expediency of implementation consists of changing the conditions in such a way that the implementation of the original rulings and laws is not possible and the rulings and laws conflict with each other.