Lewis Ross earned a bachelor's degree from Miami University. After several years practicing law in Ohio, he moved to Iowa in 1861. In 1863, he was elected to the State Senate. The following year he was appointed a regent of the state's university system. He joined the law faculty at Iowa as a lecturer in 1875, and a resident professor in 1880.
He was elected Chancellor of the Law Department in 1881, and served until 1887. As Chancellor, he oversaw the law school's move into the Old Capitol building. He died in 1902.