Indian Penal Code, 1860
Chapter VIII - Of Offences against the Public Tranquility
IPC Section 145
Joining or continuing in unlawful assembly, knowing it has been commanded to disperse.
Whoever joins or continues in an unlawful assembly, knowing that such unlawful assembly has been commanded in the manner prescribed by law to disperse, shall be punished with imprisonment of either description for a term which may extent to two years, or with fine, or with both.