Section 141 of Indian Penal Code. "Unlawful Assembly" An assembly of five or more persons is designated an "unlawful assembly", if the common object of the persons composing that assembly is-
First- To overawe by criminal force, or show of criminal force, 87[the Central or any State Government or Parliament or the Legislature of any State], or any public servant in the exercise of the lawful power of such public servant; or Second- To resist the execution of any law, or of any legal process; or Third- To commit any mischief or criminal trespass, or other offence; or
Fourth- By means of criminal force, or show of criminal force, to any person, to take or obtain possession of any property, or to deprive any person of the enjoyment of a right of way, or of the use of water or other incorporeal right of which he is in possession or enjoyment, or to enforce any right or supposed right; or Fifth- By means of criminal force, or show of criminal force, to compel any person to do what he is not legally bound to do, or to omit to do what lie is legally entitled to do. Explanation- An assembly which was not unlawful when it assembled, may subsequently become an unlawful assembly.
Section 142 of Indian Penal Code. "Being a member of Unlawful Assembly"
Whoever, being aware of facts which render any assembly an unlawful assembly, intentionally joins that assembly, or continues in it, is said to be a member of an unlawful assembly.
Section 143 of Indian Penal Code. "Punishment for Unlawful Assembly"
Whoever is a member of an unlawful assembly, shall be punished with imprisonment of either description for a term which may extend to six months, or with fine, or with both.