16. The emphasis in Section 149 IPC is on the common object and not on common intention. Mere presence in an unlawful assembly cannot render a person liable unless there was a common object and he was actuated by that common object and that object is one of those set out in Section 141. Where common object of an unlawful assembly is not proved, the accused persons cannot be convicted with the help of Section 149. The crucial question to determine is whether the assembly consisted of five or more persons and whether the said persons entertained one or more of the common objects, as specified in Section 141. It cannot be laid down as a general proposition of law that unless an overt act is proved against a person, who is alleged to be a member of an unlawful assembly, it cannot be said that he is a member of an assembly. The only thing required is that he should have understood that the assembly was unlawful and was likely to commit any of the acts which fall within the purview of Section 141. The word "object" means the purpose or design and, in order to make it "common", it must be shared by all. In other words, the object should be common to the persons, who compose the assembly, that is to say, they should all be aware of it and concur with it. A common object may be formed by express agreement after mutual consultation, but that is by no means necessary. It may be formed at any stage by all or a few members of the assembly and the other members may just join and adopt it. Once formed, it need not continue to be the same. It may be modified or altered or abandoned at any stage. The expression "in prosecution of common object" as appearing in Section 149 has to be strictly construed as equivalent to "in order to attain the common object". It must be immediately connected with the common object by virtue of the nature of the object. There must be community of object and the object may exist only up to a particular stage, and not thereafter. Members of an unlawful assembly may have community of object up to a certain point beyond which they may differ in their objects and their knowledge, possessed by each member of what is likely to be committed in prosecution of their common object which may vary not only according to the information at his command, but also according to the extent to which he shares the community of object, and as a consequence of this the effect of Section 149 IPC may be different on different members of the same assembly.
17. "Common object" is different from a "common intention" as it does not require a prior concert and a common meeting of minds before the attack. It is enough if each has the same object in view and their number is five or more and that they act as an assembly to achieve that object. The "common object" of an assembly is to be ascertained from the acts and language of the members composing it, and from a consideration of all the surrounding circumstances. It may be gathered from the course of conduct adopted by the members of the assembly. What the common object of the unlawful assembly is at a particular stage of the incident is essentially a question of fact to be determined, keeping in view the nature of the assembly, the arms carried by the members, and the behaviour of the members at or near the scene of the incident. It is not necessary under law that in all cases of unlawful assembly, with an unlawful common object, the same must be translated into action or be successful. Under the Explanation to Section 141, an assembly which was not unlawful when it was assembled, may subsequently become unlawful. It is not necessary that the intention or the purpose, which is necessary to render an assembly an unlawful one comes into existence at the outset. The time of forming an unlawful intent is not material. An assembly which, at its commencement or even for some time thereafter, is lawful, may subsequently become unlawful. In other words it can develop during the course of incident at the spot eo instanti.
18. Section 149 IPC consists of two parts. The first part of the section means that the offence to be committed in prosecution of the common object must be one which is committed with a view to accomplish the common object. In order that the offence may fall within the first part, the offence must be connected immediately with the common object of the unlawful assembly of which the accused was a member. Even if the offence committed is not in direct prosecution of the common object of the assembly, it may yet fall under Section 141, if it can be held that the offence was such as the members knew was likely to be committed and this is what is required in the second part of the section. The purpose for which the members of the unlawful assembly set out or desired to achieve is the object. If the object desired by all the members is the same, the knowledge that is the object which is being pursued is shared by all the members and they are in general agreement as to how it is to be achieved and that is now the common object of the assembly. An object is entertained in the human mind, and it being merely a mental attitude, no direct evidence can be available and, like intention, has generally to be gathered from the act which the person commits and the result therefrom. Though no hard-and-fast rule can be laid down under the circumstances from which the common object can be culled out, it may reasonably be collected from the nature of the assembly, arms it carries and behaviour at or before or after the scene of incident. The word "knew" used in the second branch of the section implies something more than a possibility and it cannot be made to bear the sense of "might have been known". Positive knowledge is necessary. When an offence is committed in prosecution of the common object, it would generally be an offence which the members of the unlawful assembly knew was likely to be committed in prosecution of the common object. That, however, does not make the converse proposition true; there may be cases which would come within the second part but not within the first part. The distinction between the two parts of Section 149 cannot be ignored or obliterated. In every case it would be an issue to be determined, whether the offence committed falls within the first part or it was an offence such as the members of the assembly knew to be likely to be committed in prosecution of the common object and falls within the second part. However, there may be cases which would be within the first part but offences committed in prosecution of the common object; would be generally, if not always, be within the second part, namely, offences which the parties knew to be likely to be committed in the prosecution of the common object.