Samuel R. Rosenthal was born in Manistique, Michigan. He served as a lieutenant in the army during World War I and later earned his undergraduate degree from the University of Michigan in 1921. He obtained his law degree from Harvard University in 1924.
In 1926, Rosenthal began work at Chicago’s Sonnenschein law firm. He eventually became a senior partner at the firm, working there for a total of 68 years.
He married Marie-Louise Dreyfus in 1932, with whom he financed a gallery at the Art Institute of Chicago. They had two children, Martin and Louise (Glasser).
Rosenthal was on the Board of Trustees at The Newberry Library, a trustee of the Ravinia Festival Association, Highland Park Public Library and Grinnell College, and a life trustee of the Highland Park Hospital Foundation. He also served as president of the Highland Park Community Chest and Board of Education of Highland Park High School. Rosenthal was a fellow of Brandeis University and the Morgan Library. He was a member of the American Antiquarian Society, the Chicago, American and Illinois bar foundations and Phi Beta Kappa. Harvard Law School named the Samuel R. Rosenthal Professorship of Law in his honor.