David P. O'Neil is one of the firm's founding partners and the firm's current Managing Partner. He is a graduate of St. Mary's School of Law in San Antonio, Texas. He holds an advanced law degree (L.L.M.) from the United States Army Judge Advocate General (JAG) School. O'Neil is a retired United States Marine Corps Lieutenant Colonel who began his military service as an infantry officer. During his military career with the Marines he headed a Legal Defense Counsel Service at Camp Lejeune, North Carolina and served as the Marines' Chief Legal Defense Counsel for Okinawa, Japan. At Marine Corps Headquarters O'Neil served as the Executive Secretary for the Joint Services Committee on Military Justice, drafting changes to the Manual for Courts-Martial and the Uniform Code of Military Justice. He served as the Marine Representative to the U.S. Army Judge Advocate General (JAG) School, as an Assistant Staff Judge Advocate to the Commander-in-Chief of the U.S. Pacific Command, and as the Staff Judge Advocate for Special Operations Pacific Command. Upon his retirement from the Marine Corps O'Neil became the Director of Trial Services for State Counsel for Offenders (the Texas prison public defender system). After spending five years with State Counsel, he left to join Habern and Buckley in forming the firm. O'Neil has served on the staff of the Naval War College and as an Adjunct Professor at Sam Houston State University in Huntsville. He has authored several significant trial litigation manuals and articles and has testified before the Texas Legislature on criminal justice issues. He is currently Chairman of the Corrections Law Committee of the Texas Criminal Defense Lawyers Association.