David P. O’Neil began his professional career in the United States Marine Corps, serving as an infantry officer. While in the Corps he attended St. Mary’s Law School in San Antonio, Texas, where he graduated with a law degree in 1979. He went on to receive an L.L.M. from the United States Army Judge Advocate General’s (JAG) School. After 21 years of active service in the Corps he retired as a Lieutenant Colonel. Among his many assignments with the Marine Corps he headed a Defense Counsel Service at Camp Lejeune, North Carolina, served as the Marines’ Chief Legal Defense Counsel for Okinawa, Japan, served as the Executive Secretary for the Joint Services Committee on Military Justice, and was the Staff Judge Advocate for Special Operations Pacific Command. He also taught law on the staff of the United States Naval War College and The United States Army Judge Advocate General’s School.
Upon his retirement from the Marine Corps he became the Director of Trial Services for State Counsel for Offenders (the Texas prison public defender system) for five years. In that capacity he represented hundreds of inmates around the state who were accused of committing various felonies while incarcerated in the Texas Department of Criminal Justice. He also supervised nearly a dozen attorneys involved in trial and appeals of other inmates. As the Director of Trial Services, he took a trial program that the previous Director described as winning “one case a year” to a program that won more cases than they lost, and where, as a result, plea offers on virtually all other cases were dramatically improved. In 2000, he resigned that position to join Bill Habern in a practice focusing on parole and prison matters. He was the Managing Partner of the Habern & O’Neil Law Firm for over a decade before opening the Law Office of David P. O’Neil, P.C., in 2016. He currently is a Co-Chairman of the Texas Criminal Defense Lawyers Association (TCDLA) Corrections & Parole Committee, and has served in that capacity for over a decade.
Mr. O’Neil has been a guest speaker at many TCDLA and local Bar Association legal seminars. He has authored and co-authored numerous articles, including articles that have been published in the Texas Criminal Defense Lawyers magazine, Voice for the Defense, and articles he has written for seminars where he has been asked to speak on parole and parole related topics. Among his numerous articles are: