Justice Cornelius J. O'Brien was born on November 3, 1931 in New York. He graduated from Fordham University in 1954 and Fordham University School of Law in 1959. He was then engaged in the private practice of law and worked for the Federal Government. In 1967, O'Brien began work at the Queens County District Attorney's office. There, he served as Chief of the Appeals Bureau from 1970 until 1974 and as Executive Assistant District Attorney from 1974 until 1977.
He joined the bench in 1977 when he was appointed to the Criminal Court. In 1982, he began serving as an Acting Supreme Court Justice. Justice O'Brien won election to the Supreme Court for the Eleventh Judicial District in 1988. Two years later, he was designated to the Appellate Division, Second Department by Governor Mario M. Cuomo and served until his death.
In addition to his judicial career, Justice O'Brien was a member of the Queens County Bar Association, Queens County District Attorney's Association, Supreme Court Judges Association, and had served as chairperson of the New York City Criminal Court Judge's Training Seminar and the New York State Judge's Seminar. He was also a veteran of the U.S. Army, having served from 1954 until 1956.
He was married to Alice Dunn and had one daughter. He died on February 9, 2003.
Appellate Division, Second Department, 100th Anniversary. 22. The Historical Society of the Courts of the State of New York, 1996. Web. 11 Jun. 2012. http://www.courts.state.ny.us/history/pdf/Library/Courts/App_Div_Sec_Dept_100th_Anniv.pdf.
"Cornelius J. O'Brien." Biographical information sheets. Appellate Division, Second Department Library, Brooklyn.
"Deaths." New York Times (1923-Current file): B9. ProQuest Historical Newspapers: The New York Times (1851-2008). Feb 11 2003. Web. 11 June 2012.