About John S.
John S. Leonardo earned his law degree from The George Washington University Law School in 1972 after undergraduate studies at the University of Notre Dame. He entered the legal profession at a time of change in Washington and carried that early training into a long career in public service and litigation. His education laid a foundation in federal law that shaped later roles in government work.
Leonardo's professional record includes service in the United States Attorney’s Office for the District of Arizona. In 2012 he served as the United States Attorney for the District of Arizona, a role that placed him at the center of federal criminal prosecutions and civil litigation involving the federal government in the state. The position required managing a large office of prosecutors and support staff and overseeing cases that ranged from organized crime and drug enforcement to white-collar matters and civil actions on behalf of the United States.
Over decades, Leonardo handled matters that demanded an understanding of both courtroom practice and policy considerations. He developed experience in federal investigative processes, grand jury work, and the coordination of multiagency efforts. Colleagues and court records reflect a practitioner accustomed to high-volume dockets and the procedural complexities of federal practice. Those responsibilities often involved collaboration with federal law enforcement and state and local partners.
His time in federal service also included responsibilities beyond casework. Running an office required managerial decisions about priorities, resource allocation, and prosecutorial discretion. The role required balancing public safety concerns with constitutional protections and procedural fairness. Such administrative duties are a regular, but sometimes overlooked, part of senior roles in a U.S. Attorney’s Office.
After his tenure as a federal prosecutor, Leonardo continued to be associated with matters tied to federal law. He has remained active in legal circles that address federal criminal law and civil litigation involving the government. In court filings and public records, his work reflects steady involvement in the kinds of cases that typically come before a District of Arizona docket.
As of 2026, Leonardo concentrates his practice on matters arising under federal statutes and on litigation that touches the interests of the United States in Arizona.
