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 South Dakota, the criminal offense of unlawful assembly is addressed under the state's penal code. Specifically, South Dakota Codified Laws (SDCL) define unlawful assembly as a gathering of three or more persons with the intent to commit an unlawful act or in a manner that is likely to result in a breach of the peace. The law also covers related offenses such as rioting, which involves a group of people engaging in violent conduct or creating a clear and present danger of violent conduct. Additionally, the statutes address the failure to disperse when a group of people, being ordered to disperse by a law enforcement officer, do not do so and thereby intentionally cause a substantial risk of causing injury to others or damage to property. Penalties for these offenses can vary, but they generally include fines, imprisonment, or both. An attorney can provide specific guidance on how these laws might apply to a particular situation, taking into account the nuances of the state statutes and relevant case law.