(A) Tamil Nadu General Sales Tax Act (1 of 1959) , S.32, S.34— Revision - Power conferred on Deputy Commissioner - Scope - Person aggrieved can move Deputy Commissioner to exercise suo motu power of revision. If a statute invites a public officer with authority to do an act in a specified set of circumstances, it is his duty to exercise that power which is invested in aid of enforcement of a right. The suo motu power of revision under Section 32 of the Act is conferred on the Deputy Commissioner to ensure that injustice to the assessee or to the revenue is avoided. The exercise of that power by the Deputy Commissioner is not discretionary, and if conditions for exercise of that power are shown to exist, the Deputy Commissioner cannot decline to exercise that power. Otherwise, he can be compelled to exercise that power by issue of a writ of mandamus by High Court. Such being the scope, extent and width of the power of the Deputy Commissioner under Section 32, it is incorrect to state that the power can be exercised only by the authority vested with that power. Any party aggrieved could move the Deputy Commissioner to exercise the suo motu power of revision. If the Deputy Commissioner fails to exercise his jurisdiction under Section 32, any person aggrieved could move the Deputy Commissioner to exercise the suo motu power of revision. There is nothing in law p....