A Career of Service, Leadership, and Accountability

David O’Neil brings more than three decades of public service experience to his role as Williamson County Commissioner. His career has spanned law enforcement, legal practice, and public leadership, with a consistent focus on accountability, sound judgment, and service to the community.

He retired in 2024 from the Brentwood Police Department, where he served in several leadership roles including Captain of the Criminal Investigations Division. During his career, he was responsible for managing complex investigations, supervising personnel, developing policy, overseeing budgets, and working closely with local, state, and federal agencies.

Leadership in Law Enforcement

Throughout his law enforcement career, David served in a wide range of roles, from patrol officer and K-9 handler to detective, supervisor, and division commander. As a Captain, he oversaw major investigations, managed personnel and resources, and worked closely with prosecutors and partner agencies to ensure cases were handled professionally and lawfully.

He also played a key role in developing training programs, improving investigative practices, and strengthening departmental policies. His work included participation in multi-agency task forces with the Tennessee Bureau of Investigation, the Federal Bureau of Investigation, and the United States Secret Service.

His leadership experience gives him a practical understanding of public safety, budgeting, personnel management, and long-term planning.

Legal Experience and Policy Work

In addition to his law enforcement career, David has practiced law since 2008. He has served as a public sector attorney, advising on contracts, policy development, open records compliance, employment matters, and legal procedures.

He also served as a Special Assistant District Attorney, handling court proceedings including probable cause hearings, suppression hearings, and criminal prosecutions. His legal background gives him a strong understanding of how laws, policies, and budgets intersect, an important perspective for county government.

Teaching, Training, and Professional Development

David has spent much of his career teaching and training others. He has served as an adjunct professor in criminal law and constitutional law, instructed law enforcement officers across Tennessee, and presented at state and national training conferences.

He has taught subjects including constitutional law, search and seizure, criminal procedure, leadership, and professional ethics. His work as an instructor reflects a long-standing commitment to education, accountability, and professional standards.

Service as County Commissioner

In 2024, David was elected to serve as Williamson County Commissioner for District 6. In this role, he works with fellow commissioners to oversee county operations, approve budgets, and address issues affecting residents across the county.

His experience in leadership, budgeting, and policy analysis allows him to approach county issues with a steady, informed perspective. He focuses on responsible growth, public safety, infrastructure planning, and careful use of taxpayer dollars.

David O’Neil’s career reflects a consistent commitment to public service, responsible leadership, and doing what is right for the community. As County Commissioner, he continues to bring that same dedication and experience to serving the residents of Brentwood and Williamson County.

His experience allows him to evaluate complex issues, balance competing priorities, and make decisions that are both practical and legally sound.