Every authority is invested with certain powers within the scope of the Act which creates it. The authority shall act within the scope of the powers conferred on it, if it transgresses and does anything over and above, it is said exceed its powers. If it violates its powers, the authority is said to abuse its powers. A Police Officer can arrest a person if the offence is cognizable. If he wrongfully arrests a person in a case which is not cognizable by police he acts in excess of his powers. If he knowingly, willfully and with mala fide and oblige motive arrests a person which the power he does not have should be treated as acting in abuse of powers. A Sales Tax Officer if he includes in the taxable turnover, the transactions of purchase and sale which do not come within their sweep it is possible that he may have committed an error in exercising his powers, but if he has done deliberately with a view to cause hardship to the assessee or with any oblique motives he is said to have made the assessment in abuse of his powers. Thus, if the authority acts without jurisdiction or in excess of jurisdiction it may do so innocently, and if the authority acts with motives questionable it shall be deemed to have acted in abuse of his powers. A person who gains by exercising his powers mala fide or for purposes other than those contemplated under the laws he shall not be permitted to retain such gains for that would amount to favouring him with unjust enrichment. Such gains are liable to be forfeited to the State. A person who is acting in abuse of his powers or under the cover of the authority or assuming its garb is liable to be prosecuted and punished under criminal law. All orders made and actions taken in abuse of powers by any authority, are liable to be set aside as void ab initio.
Abuse of power may be legislative, Executive, judicial and also Administrative. If the legislature passes an enactment targeting a particular individual to certain detriment either prospectively or retrospectively, the legislature acts in abuse of its powers, even though the subject matter falls within the subject of the legislation. There was an instance where Andhra Pradesh Legislative Assembly passed an Act curtailing the tenure of office of a Vice-Chancellor. Similarly by altering the age of retirement the Parliament retired the Director of a Central Institute of Higher Education. Both these enactments were declared ultra vires. In the case of executive and administrative orders, it is impermissible for any authority to make an order in a manner which is discriminatory and invidious. There was a case of a High Court Judge upholding patently irregular allotments of plots made by co-operative society in which the Judge himself happened to be a beneficiary in such allotment, which order of the Judge was set aside by the Supreme Court as one made in abuse of the powers of the concerned Judge. Abusing of powers occurs more out of temptation for deviation. It need not necessarily be motivated by corrupt practices. Where abuse of power occurs, it is not a case for striking down any provision in the enactment which confers arbitrary and discretionary powers. But what is struck down is the act by which the power is abused.
[Ref.: Sriram Ram Narayan v. State of Bombay, AIR 1959 SC 459.]