Before Francis J. Rosenthal became a lawyer, he was a "musical instructor, choir master, and soloist" in operas and symphonies around the country. He "abandoned" his music career in 1910, and entered the St. Paul College of Law. Admitted to the bar in 1914, he practiced law in St. Paul until his death on August 22, 1932, at age fifty-five.
Unlike many lawyers, he was an introvert, but that characteristic may have given confidence and reassurance to his clients. As the Committee of the Ramsey County Bar Association, which presented a memorial to him on April 15, 1933, recalled: "The trials and disappointments which he experienced were buried within him, to be shared with no one. To those with whom he came in contact, he conveyed nothing but comfort, encouragement and inspiration."