Justice Isaac N. Mills was born on September 10, 1851, in Thompson, Windham County, Connecticut. His family had come from England in 1630 and had been farmers for eight generations. Mills attended Providence Conference Seminary and Amherst College before graduating from Columbia Law School in 1876. He was admitted to the bar that year and began practicing law at the firm of Mills & Wood in Mount Vernon.
Mills joined the bench in 1883 when he won election as Westchester County Judge. He was re-elected to that post six years later. In 1990, he was elected to the State Senate for the Twenty-second District. In 1906 and again in 1920, Mills was elected to the Supreme Court for the Ninth Judicial District. He was designated to the Appellate Division, Second Department in 1917 by Governor Whitman. After 27 years on the bench, he retired in 1921, noting his pleasure at never having had to impose a sentence of capital punishment, despite presiding over several murder trials during his career. Following his retirement, Mills continued to serve as an official referee for the Supreme Court and continued to practice law until the final months of his life.
His membership in professional organizations included the New York State, New York City and Westchester County Bar Associations and the Amherst College alumni organization. He was also active in fraternal organizations and fishing and hunting clubs.
He was married to Cara Maria Burnett on December 18, 1876 and had four children. He died on July 14, 1929 at his home in Mount Vernon at the age of 78, due to an illness following an operation.
"Isaac N. Mills Dies; was Noted Jurist." New York Times (1923-Current file): 16. ProQuest Historical Newspapers: The New York Times (1851-2008). Jul 15 1929. Web. 22 May 2012 .
"Sent no One to Death in 27 Years as Judge." New York Times (1857-1922): 25. ProQuest Historical Newspapers: The New York Times (1851-2008). Jan 01 1922. Web. 22 May 2012 .