In 1761, a group of outraged Boston businessmen which included Ezekiel Goldthwait engaged Otis to challenge the legality of "writs of assistance" before the Superior Court, the predecessor of the Massachusetts Supreme Judicial Court. These writs enabled the authorities to enter any home with no advance notice, no probable cause, and no reason given.
Otis considered himself a loyal subject to the Crown, yet he argued against the writs of assistance in a nearly five-hour oration before a select audience in the State House in February 1761. His argument failed to win his case, but it galvanized the revolutionary movement. John Adams recollected years later: "Otis was a flame of fire; with a promptitude of classical allusions, a depth of research, a rapid summary of historical events and dates, a profusion of legal authorities." Adams promoted Otis as a major player in the coming of the Revolution. Adams said, "I have been young and now I am old, and I solemnly say I have never known a man whose love of country was more ardent or sincere, never one who suffered so much, never one whose service for any 10 years of his life were so important and essential to the cause of his country as those of Mr. Otis from 1760 to 1770." Adams claimed that "the child independence was then and there born, every man of an immense crowded audience appeared to me to go away as I did, ready to take arms against writs of assistance."