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 Nebraska, the criminal offense of unlawful assembly is addressed under the state's penal code. Specifically, Nebraska Revised Statute 28-727 defines unlawful assembly as the gathering of three or more persons with the intent to use force or violence to commit any unlawful act, or their conduct is likely to cause a substantial risk of causing injury to persons or property, or they substantially obstruct law enforcement or other government functions. The statute also covers related offenses such as rioting, which is defined under Nebraska Revised Statute 28-728, where seven or more persons are involved in the use of force or violence, thereby disturbing the peace. The penalties for these offenses can vary, but they generally include fines, imprisonment, or both. It is important for individuals to understand that participating in a protest or demonstration is legal, provided it is peaceful and does not infringe on the rights of others or violate the law. An attorney can provide specific legal advice on how these statutes may apply in individual cases or how to lawfully exercise one's right to assemble.