Rolf Jacobsen enrolled as a student in 1881, and graduated as cand.jur. in 1885. From 1885 to 1890, Jacobsen was an attorney in Nordre Gudbrandsdalen, working under district stipendiary magistrate Walter Scott Dahl. Jacobsen served as acting district stipendiary magistrate for a total of three years, while Dahl was a member of Parliament. Jacobsen then moved to Kristiania to work as a lawyer. From 1893 to 1903, he was a barrister, with access to Supreme Court cases. In 1903, he was appointed as district stipendiary magistrate in Steigen.