FIR brings law into motion. It is a written document prepared by the police when they receive information about the commission of a cognizable offence. FIR can be filed by anyone including police. FIR includes time of occurrence, date of occurrence, place of occurrence, informant name and address, accused name and address etc. It is not a substantive piece of evidence it is only used to corroborate and contradict statement of informant.
The term FIR is not defined in the Indian Penal Code (IPC), Criminal Procedure Code (CrPC) or in any other law. Section 154 CrPC prescribe the procedure for filing a FIR.
A Constitution Bench of Supreme Court in Lalita Kumari vs. State of U.P. & Ors held that Registration of FIR is mandatory under section 154 of CrPC , if the information discloses commission of a cognizable offence and no preliminary inquiry is permissible in such a situation.