The clear position therefore is that any judicial Magistrate, before taking cognizance of the offence, can order investigation u/s 156(3) of the Code. If he does so, he is not to examine the complainant on oath because he was not taking cognizance of any offence therein. For the purpose of enabling the police to start investigation it is open to the Magistrate to direct the police to register an FIR. There is nothing illegal in doing so. After all registration of an FIR involves only the process of entering the substance of the information relating to the commission of the cognizable offence in a book kept by the officer in charge of the police station as indicated in Section 154 of the Code. Even if a Magistrate does not say in so many words while directing investigating u/s 156(3) of the Code that an FIR should be registered, it is the duty of the officer in charge of the police station to register the FIR regarding the cognizable offence disclosed by the complaint because that police officer could take further steps contemplated in Chapter XII of the Code only thereafter.
Mohd. Yousuf Vs. Smt. Afaq Jahan and Another, ,
 Mohd. Yousuf Vs. Smt. Afaq Jahan and Another, AIR 2006 SC 705 : (2006) CriLJ 788 : (2006) 1 JT 10 : (2006) 1 SCALE 1 : (2006) 1 SCC 627 : (2006) 1 SCR 1 : (2006) AIRSCW 95 : (2006) 1 Supreme 6