In 1847, Caruthers and his brother, Abraham Caruthers, founded the Cumberland School of Law, one of the first law schools in the South. The school, which had an initial enrollment of seven students, held its first classes in Robert Caruthers' law office. As an instructor, Abraham Caruthers abandoned the lecture system, and instead assigned a chapter from a law text, and quizzed each student on the chapter the following day, considering this the best way to determine the areas in which a student was struggling. He also held moot courts. During the Civil War, Nathan Green, Jr., whose father had been succeeded by Robert Caruthers on the Tennessee Supreme Court in 1852, managed to keep the school open.