From 1985 until his retirement in 2009 Professor Zirkle was an Associate General Counsel with the Office of General Counsel, Central Intelligence Agency. Over his career he worked primarily in the areas of space systems, counterintelligence and security. Among his assignments were senior counsel at the National Reconnaissance Office and senior counsel to the CIA’s Counterintelligence Center and Office of Security. His last assignment was as the CIA’s Officer-in-Residence at Georgetown University’s School of Foreign Service.

He has served as an Adjunct Professor of Law at the Georgetown University Law Center and the American University’s Washington College of Law since 1988, where he teaches in the area of national security law and (at GULC) international law and covert operations.

Before joining the CIA he served as Associate Dean of the Yale Law School and has also been a member of the law faculties at the College of William & Mary and the University of Mississippi.

Prior to law school he served on active duty for five years as a line officer in the Navy.