Firstly, please note that you have mentioned that Section 324 IPC is bailable, that is not correct now. After the 2005 amendment in Criminal Procedure Code, offence under Section 324 IPC is now non-bailable.
As regards, Section 34 IPC, it may please be noted that this section does not define any separate offence. It basically defines vicarious liability when certain acts are done by several persons in furtherance of common intention. It lays down that when a criminal act is done by several persons, in furtherance of the common intention of all, each of such persons is liable for that act in the same manner as if it were done by him alone. So, all such persons having common intention would be liable for the same offence as if it was done by each one of them.
For example, if two or more persons commit an offence under Section 324 IPC in furtherance of their common intention, then they would all be charged under Section 324, 34 IPC even if only one of them had actually committed the main offence under Section 324 IPC.
It is due to this reason that since Section 34 IPC is not defined as a separate offence, it not mentioned as bailable or non-bailable in the Cr.P.C. It has to be read along with the main offence.
For example, whey you are charged under Section 324, 34 IPC, then it will be seen whether Section 324 is bailable or not. Depending on this, the nature of the case would be decided, i.e., whether it is bailable or not.
In the case of offences under Section 324, 34 IPC, the case would be non-bailable since offence under Section 324 IPC is non-bailable.
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