Section 149 IPC and the Chanda judgment become very easy if you keep three words in mind:
group, object, knowledge.
Below is a structured explanation plus a ready‑made interview answer.
1. Core idea of Section 149 IPC {S 190 of BNS}
Section 149 creates constructive / vicarious liability for members of an unlawful assembly (5 or more persons).
If one member commits an offence:
either in prosecution of the common object,
- or an offence which the members knew was likely to be committed in prosecution of that object,then every member of that assembly is guilty of that offence.
Emphasis is on common object, not on individual acts or prior “meeting of minds” as in Section 34 IPC.
