A meeting of three or more individuals to commit a crime or carry out a lawful or unlawful purpose in a manner likely to imperil the peace and tranquillity of the neighborhood.
The first amendment to the U.S. Constitution guarantees individuals the right of freedom of assembly. Under the common law and modern statutes, however, the meeting of three or more persons may constitute an unlawful assembly if the persons have an illegal purpose or if their meeting will breach the public peace of the community. If they actually execute their purpose, they have committed the criminal offense of riot.
Under the common law, when three or more individuals assembled for an illegal purpose, the offense of unlawful assembly was complete without the commission of any additional overt act. Some modern state statutes require both assembly and the commission of one of the acts proscribed by the statutes, even if the purpose of the assembly is not completed. Generally, an unlawful assembly is a misdemeanor under both common law and statutes.
The basis of the offense of unlawful assembly is the intent with which the individuals assemble. The members of the assembled group must have in mind a fixed purpose to perform an illegal act. The time when the intent is formed is immaterial, and it does not matter whether the purpose of the group is lawful or unlawful if they intend to carry out that purpose in a way that is likely to precipitate a breach of the peace.
An assembly of individuals to carry on their ordinary business is not unlawful. Conversely, when three or more persons assemble and act jointly in committing a criminal offense, such as assault and battery, the assembly is unlawful. All those who participate in unlawful assemblies incur criminal responsibility for the acts of their associates performed in furtherance of their common objective. The mere presence of an individual in an unlawful assembly is enough to charge that person with participation in the illegal gathering.
Political gatherings and demonstrations raise the most troublesome issues involving unlawful assembly. The line between protecting freedom of assembly and protecting the peace and tranquillity of the community is often difficult for courts to draw. In the 1960s, in a series of decisions involving organized public protests against racial segregation in southern and border states, the U.S. Supreme Court threw out breach-of-the-peace convictions involving African Americans who had participated in peaceful public demonstrations. For example, in Edwards v. South Carolina, 372 U.S. 229, 83 S. Ct. 680, 9 L. Ed. 2d 697 (1963), the Court held that the conviction of 187 African American students for demonstrating on the grounds of the state capitol in Columbia, South Carolina, had infringed on their "constitutionally protected rights of free speech, free assembly, and freedom to petition for redress of their grievances."
In Adderley v. Florida, 385 U.S. 39, 87 S. Ct. 242, 17 L. Ed. 2d 149 (1966), however, the Court also made clear that assemblies are not lawful merely because they involve a political issue. In this case Harriet L. Adderley and other college students had protested the arrest of civil rights protesters by blocking a jail driveway. When the students ignored requests to leave the area, they were arrested and charged with trespass. The Court held that "[t]he State, no less than a private owner of property, has power to preserve the property under its control for the use to which it is lawfully dedicated."
In general, a unit of government may reasonably regulate parades, processions, and large public gatherings by requiring a license. Licenses cannot, however, be denied based on the political message of the group. Persons who refuse to obtain a license and hold their march or gathering may be charged with unlawful assembly.