Lawful Assemblies Under the Common Law

Under the common law a lawful assembly consisted of three or more people assembled together for lawful purposes. A lawful assembly could become unlawful if it became “violent and tumultuous”. As noted in Blackstone’s Commentaries:

Riots, routs, and unlawful assemblies must have three persons at least to constitute them. An unlawful assembly is when three, or more, do assemble themselves together to do an unlawful act, as to pull down inclosures, to destroy a warren or the game therein; and part without doing it, or making any motion towards it. A rout is where three or more meet to do an unlawful act upon a common quarrel, as forcibly breaking down fences upon a right claimed of common, or of way; and make some advances towards it. A riot is where three or more actually do an unlawful act of violence, either with or without a common cause or quarrel: as if they beat a man; or hunt and kill game in another’s park, chase, warren, or liberty; or do any other unlawful act with force and violence; or even do a lawful act, as removing a nusance, in a violent and tumultuous manner. The punishment of unlawful assemblies, if to the number of twelve, we have just now seen may be capital, according to the circumstances that attend it; but, from the number of three to eleven, is by fine and imprisonment only. The same is the case in riots and routs by the common law; to which the pillory in very enormous cases has been sometimes superadded. And by the statute 13 Hen. IV. c. 7. any two justices, together with the sheriff or under-sheriff of the county, may come with the posse comitatus, if need be, and suppress any such riot, assembly, or rout, arrest the rioters, and record upon the spot the nature and circumstances of the whole transaction; which record alone shall be a sufficient conviction of the offenders. In the interpretation of which statute it hath been holden, that all persons, noblemen and others, except women, clergymen, persons decrepit, and infants under fifteen, are bound to attend the justices in suppressing a riot, upon pain of fine and imprisonment; and that any battery, wounding, or killing the rioters, that may happen in suppressing the riot, is justifiable. So that our antient law, previous to the modern riot act, seems pretty well to have guarded against any violent breach of the public peace; especially as any riotous assembly on a public or general account, as to redress grievances or pull down all inclosures, and also resisting the king’s forces if sent to keep the peace, may amount to overt acts of high treason, by levying war against the king.

The provision for freedom of assembly guaranteed by the First Amendment to the Constitution:

Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the government for a redress of grievances.

should be considered in that light. The emphasis above is mine. There is no constitutionally-guaranteed right to riot or even to assemble unlawfully. The purpose of the freedom of assembly provision is to ensure that the Congress does not make otherwise legal assemblies illegal not to render all assemblies legal.

What constitutes “violent and tumultuous”? Generally, shouting, marching, and carrying signs are all lawful. Throwing rocks is not. When rocks are thrown by those in the assembly, the assembly changes from a lawful one to an unlawful one.

This will vary somewhat from state to state. In some states the common law understanding continues to prevail; in others unlawful assembly and mob action may be defined more narrowly.