The Prevention Of Corruption Act, 1988
 S 17. Persons authorised to investigate.
Notwithstanding anything contained in the Code of Criminal Procedure, 1973 (2 of 1974), no police officer below the rank,
(a) in the case of the Delhi Special Police Establishment, of an Inspector of Police;
(b) in the metropolitan areas of Bombay, Calcutta, Madras and Ahmedabad and in any other metropolitan area notified as such under sub-section (1) of section 8 of the Code of Criminal Procedure, 1973 (2 of 1974), of an Assistant Commissioner of Police;
(c) elsewhere, of a Deputy Superintendent of Police or a police officer of equivalent rank, shall investigate any offence punishable under this Act without the order of a Metropolitan Magistrate or a Magistrate of the first class, as the case may be, or make any arrest therefor without a warrant:
Provided that if a police officer not below the rank of an Inspector of Police is authorised by the State Government in this behalf by general or special order, he may also investigate any such offence without the order of a Metropolitan Magistrate or a Magistrate of the first class, as the case may be, or makes arrest therefor without a warrant:
Provided further that an offence referred to in clause (e) of sub-section (1) of section 13 shall not be investigated without the order of a police officer not below the rank of a Superintendent of Police.
18. Power to inspect bankers books .
If from information received or otherwise, a police officer has reason to suspect the commission of an offence which he is empowered to investigate under section 17 and considers that for the purpose of investigation or inquiry into such offence, it is necessary to inspect any bankers books, then notwithstanding anything contained in any law for the time being in force, he may inspect any bankers books insofar as they relate to the accounts of the persons suspected to have committed that offence or of any other person suspected to be holding money on behalf of such person, and take or cause to be taken certified copies of the relevant entries therefrom, and the bank concerned shall be bound to assist the police officer in the exercise of his powers under this section:
Provided that no power under this section in relation to the accounts of any person shall be exercised by a police officer below the rank of a Superintendent of Police, unless he is specially authorised in this behalf by a police officer of or above the rank of a Superintendent of Police.
Explanation. In this section, the expressions banks and bankers books shall have the meanings respectively assigned to them in the Bankers Books Evidence Act, 1891.