Briggs sporadically attended the public schools in White Creek, and was apprenticed for three years to a Quaker hatter. With support from his older brothers he embarked on the study of law in Pittsfield and Lanesboro in 1813, and was admitted to the Massachusetts bar in 1818. He first opened a practice in Adams, moved it to Lanesboro in 1823, and Pittsfield in 1842. His trial work was characterized by a contemporary as clear, brief, and methodical, even though he was fond of telling stories in less formal settings.