In 1986, he was appointed by President Ronald Reagan to be a judge on the U.S. Court of Appeals for the Ninth Circuit. In that role, he has participated in over 6,000 cases and authored hundreds of published opinions. His professional interests include judicial administration and reform, as well as continuing legal education. The late Chief Justice Rehnquist appointed Judge O’Scannlain to the Federal Judicial Center’s Advisory Committee on Appellate Judge Education. He also previously chaired the Judicial Division of the American Bar Association, the ABA’s Appellate Judge’s Conference, its Committee on Appellate Practice, and its 9th Appellate Practice Institute. He also serves on the faculty of the New York University Law School’s Institute for Judicial Administration and the Lewis & Clark Law School.