James Otis was called the most important American of the 1760s by John Adams. A trained lawyer and master of argument, James Otis was a leader of the Patriot movement in Boston in those years. Initially a prosecutor for the British authorities, Otis changed sides in 1761, when he argued against writs of assistance (broad search warrants that British officials used to search the homes and businesses of colonists). During the 1760s, Otis led the intellectual attack against British tyranny, composing ringing defenses of liberty that won Americans to the revolutionary cause and helped to inspire the well-known slogan, "No taxation without representation."