Section 34 and section 149 of the Indian Penal Code are substantive in nature as they do not provide any punishment.
Understanding Section 34 IPC
Section 34 of IPC talks of acts done by two or more persons in furtherance of common intention. Each person will be liable for the offence committed. It is immaterial, what role a person is playing in the act. It can be the primary or main act, or it can be an auxiliary or secondary act. Even if a person stands at the door so that offence can take place, he is liable.
Understanding Section 149 IPC
Whereas section 149 of IPC says that every member of the unlawful assembly will be held guilty for the offence committed ian prosecution of a common object. It is not necessary for all members to actively participate in the crime. Even if a single individual commits the offence, all will be held liable for being a member of unlawful assembly.
Which one is Graver? Section 302/34 or Section 302/149
Law students out of inquisitiveness ask about the gravity of these sections when reading with section 302 of IPC (murder). They wonder which of these leads to stricter punishment.
It depends upon what offence is done as they both are not providing punishment but imputing punishment on those who did not do the grave offence. But because they are sharing common intention or common object, they are being held liable. So, the harshness of the punishment depends from case to case and facts to facts.