The criminal offense of unlawful assembly generally means the assembly of multiple persons resulting in conduct that (1) is intended to commit a breach of the peace or other unlawful act; (2) creates an immediate danger of damage to property or injury to persons; (3) substantially obstructs law enforcement or other governmental functions or services; (4) is tumultuous or violent and likely to cause public alarm; or (5) deprives any person of a legal right or disturbs any person in the enjoyment of a legal right by using force or the threat of force.

Unlawful assembly laws vary from state to state and some states have related offenses such as rioting, riots and routs, participating in a riot, inciting a riot, failing to disperse, and disturbing the peace. The criminal offense of unlawful assembly may be included in the definition of one or more of these offenses or may be a separate criminal offense. These laws are generally located in a state’s statutes—often in the penal or criminal code.

In California, the criminal offense of unlawful assembly is defined under California Penal Code Section 407 and 408. An unlawful assembly occurs when two or more persons assemble together to do an unlawful act, or to do a lawful act in a violent, boisterous, or tumultuous manner. The law is designed to prevent disorder and maintain public peace. Under Section 409, individuals present at an unlawful assembly who have been lawfully commanded to disperse but fail to do so may also be charged with a misdemeanor. Related offenses include rioting, inciting a riot, and disturbing the peace, which are covered under different sections of the Penal Code. For example, California Penal Code Section 404 covers riots, and Section 404.6 addresses incitement to riot. These laws are enforced to ensure that while individuals have the right to assemble and protest, they must do so without resorting to violence or disrupting public order.