Dictionary.net

a vigorous reprimand; "I read him the riot act"

a former English law requiring mobs to disperse after a magistrate reads the law to them

a vigorous reprimand; "I read him the riot act"

a former English law requiring mobs to disperse after a magistrate reads the law to them

Passed by Parliament for the prevention of tumultuous assemblies; after the reading of which to a mob by a civil magistrate, if they do not disperse, troops may fire upon them until they have brought them to order.