Janet James Mahon serves as an Administrative Law Judge in the District of Columbia Office of Administrative Hearings. Prior to joining the Office of Administrative Hearings, she served as the Deputy General Counsel for the District of Columbia Office of Tax and Revenue, and as an Attorney-Advisor for the United States Treasury Department, Financial Management Service. 

Judge Mahon is active in the legal community, serving as chair of the Public Education Outreach Subcommittee for the National Association of Administrative Law Judges, Secretary of the Women’s Bar Association of Washington, DC, and Steering Committee Member for the Taxation Section of the District of Columbia Bar Association. Judge Mahon's bar memberships include the District of Columbia Court of Appeals, the Pennsylvania Supreme Court, the Massachusetts Supreme Judicial Court and the Supreme Court of the United States. Judge Mahon recently published, “Joint Ventures Between Non-Profit and For-Profit Organizations: The St. David’s Case – Worthy Destination, But Road Under Construction,” The Tax Lawyer, Vol. 56, No. 4, Summer 2003.

Judge Mahon graduated from Pennsylvania State University with a Bachelor of Science degree in labor and industrial relations; Boston College Law School, JD; and Georgetown Law School, LLM in Taxation. She is also a certified public manager (certificate in public management, George Washington University).