Section 149 consists of two parts, the first part of 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 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 member s 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 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 persons commit and the result there from.

Though no hard and fast rule can be laid down under the circumstances from which the common object can be called out ,it may be reasonably be collected from the nature of the assembly, arms it carries and behaviour at the time of or before or after the occurrence. The word knew used in the second limb of the section implies something more than a possibility and it can not 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 prosecution true, there may be cases which would come within the second part but not within the first part.