Section 157(1) CrPC reads as follows: If, from information received or otherwise, an officer in charge of a police station has reason to suspect the commission of an offence which he is empowered under section 156 to investigate, he shall forthwith send a report of the same to a Magistrate empowered to take cognizance of such offence upon a police report and shall proceed in person, or shall depute one of his subordinate officers not being below such rank as the State Government may, by general or special order, prescribe in this behalf, to proceed, to the spot, to investigate the facts and circumstances of the case, and, if necessary, to take measures for the discovery and arrest of the offender: Provided that— (a) when information as to the commission of any such offence is given against any person by name and the case is not of a serious nature, the officer in charge of a police station need not proceed in person or depute a subordinate officer to make an investigation on the spot; (b) if it appears to the officer in charge of a police station that there is no sufficient ground for entering on an investigation, he shall not investigate the case.
Under Section 157(1)(b) if it appears to a Police Officer that there is no sufficient ground for entering on an investigation he shall not investigate the case and the officer should inform the informant under the prescribed manner.
The question is whether this discretion is available to a police officer if the investigation is being made pursuant to an order of a Magistrate?
The Karnataka High Court in Guruduth Prabhu vs. M.S.Krishna Bhat, 1999 Cri.LJ 3909 has observed that once the Magistrate orders an investigation under Section 156(3), Cr. P.C. the Police Officer is bound to investigate the matter and there is no question of his deciding not to investigate. Thus, by an order of the Magistrate under Section 156(3) the discretion given to the Police Officer under Section 157 is taken away. This observation was made in the context of highlighting the importance of application of mind by the Magistrate before ordering investigation.