He attended Williams College, and graduated from Yale College in 1808. Then he studied law in Troy with John D. Dickinson, was admitted to the bar in 1811, and commenced practice in Cazenovia. On September 12, 1813, he married Louise Whipple, and they had nine children, among them California Assemblyman John W. Dwinelle (1816–1881). Justin Dwinell was member of the New York State Assembly (Madison Co.) in 1820–21 and 1822. He was First Judge of the Madison County Court from 1823 to 1828. Dwinell was elected as a Crawford Democratic-Republican to the 18th United States Congress, holding office from March 4, 1823, to March 3, 1825. He was District Attorney of Madison County from 1837 to 1845. He was buried at the Evergreen Cemetery in Cazenovia, New York.
Aged: 80.2 years
"married Justin Dwinell 9/12/1813,had 9 children,7 whom reach adulthood,5 sons & 2 daughters,3 Lawyers & 2 doctors.Son John Esq. born9/9/1816 served in California State Assembly,responsible for the creation of the University of California 1868.Dwinell Hall at UC Berkeley.He was Mayor of Oakland,Cal.1864. died 1881 buried at Cypress Lawn Memorial Park,Colma,Cal."