# Thomas D. O'Brien *Minnesota lawyer, county attorney, insurance commissioner and state supreme court justice (1859–1935)* Thomas Dillon O'Brien (February 14, 1859 – September 3, 1935) was a Minnesota lawyer, judge and legal educator. He was a justice of the [[Minnesota Supreme Court]] and one of five co-founders of William Mitchell College of Law.[^1] His public career ran through St. Paul's legal offices and state government. He was clerk of the St. Paul Municipal Court, Assistant City Attorney, [[Ramsey County Attorney]] for one term, and state Insurance Commissioner. Governor [[John Albert Johnson]] appointed him to the supreme court in 1909, and he left the bench in 1911.[^2] ## Biography O'Brien was born at La Pointe, on Madeline Island in Wisconsin, on February 14, 1859. His family moved to St. Paul, Minnesota, when he was four.[^2] He prepared for the law by reading with a local practitioner and was admitted to the Minnesota bar in 1880. His first legal post was clerk of the St. Paul Municipal Court. He became Assistant City Attorney in 1885. In 1891 he won election as Ramsey County Attorney and held the office for a single term.[^2] In 1900 he joined Hiram F. Stevens, Ambrose Tighe, Moses Clapp and Clarence Halbert in establishing the St. Paul law school from which William Mitchell College of Law descends. He was on its faculty for much of the 1900s.[^1][^2] O'Brien was the state Insurance Commissioner from 1905 to 1907. In September 1909, Governor Johnson named him an associate justice of the Minnesota Supreme Court. He left the court in 1911 and went back to private practice. He was later dean of the St. Thomas College of Law until that school dissolved in 1933.[^2] O'Brien died in St. Paul on September 3, 1935. He is buried in Calvary Cemetery.[^2] ## In the Minnesota record ### Who - Thomas Dillon O'Brien, lawyer, judge and academic from [[Minnesota]]; co-founder of William Mitchell College of Law.[^1] ### What - Associate justice of the Minnesota Supreme Court, appointed September 1909; left the court in 1911.[^2] - Minnesota Insurance Commissioner, 1905–1907.[^2] - Ramsey County Attorney, elected 1891, one term.[^2] - Dean of the St. Thomas College of Law until its dissolution in 1933.[^2] ### When - Born February 14, 1859; died September 3, 1935.[^2] - Admitted to the Minnesota bar in 1880; Assistant City Attorney in 1885.[^2] ### Where - Born at La Pointe, Madeline Island, Wisconsin; moved to St. Paul at age four; died in St. Paul; buried at Calvary Cemetery.[^2] ### How - Reached the supreme court by gubernatorial appointment from Governor Johnson in September 1909. Reached the county attorney's office by election in 1891.[^2] ### How many - One term as Ramsey County Attorney.[^2] ## Notes [^1]: Wikipedia contributors, *Thomas D. O'Brien* (revision 1374168342, retrieved 2026-10-26), lead section — identifies him as a lawyer, judge and academic, a Minnesota Supreme Court justice, and one of five co-founders of William Mitchell College of Law. https://en.wikipedia.org/wiki/Thomas_D._O'Brien [^2]: Wikipedia contributors, *Thomas D. O'Brien* (revision 1374168342, retrieved 2026-10-26), "Biography" section — birth, bar admission, municipal and county offices, Insurance Commissioner term, 1909 appointment by Governor Johnson, 1911 departure, deanship, death and burial. https://en.wikipedia.org/wiki/Thomas_D._O'Brien