In 1950, President Harry S. Truman appointed Roberts the United States District Judge for the District of Puerto Rico. He returned to Rhode Island and was appointed Associate Justice of the Superior Court of Rhode Island in 1951. In 1955, he was appointed Associate Justice of the Supreme Court of Rhode Island. He served on the Rhode Island Supreme Court until 1976, from 1966 to 1976 as Chief Justice.
Judge Thomas Hagan Roberts was born in Providence, Rhode Island on January 4, 1902, the older of two sons born to Dennis J. Roberts and Mary (Hagan) Roberts. He studied at LaSalle Academy, received his Bachelor of Arts Degree from Fordham University in 1927 and his law degree in 1931 from Boston University School of Law.
His brother Dennis was Mayor of Providence from 1941 to 1951, and Governor of Rhode Island from 1951 to 1959.
Judge Roberts married Florence E. McCabe on July 29, 1939. They had two sons, Dennis J. Roberts II, who served three terms as Attorney General of Rhode Island from 1979 to 1985, and Thomas H. Roberts, Jr., a Professor of History at Rhode Island School of Design.
Judge Roberts died on January 7, 1976.