Irvin Nathan counsels and represents individuals, corporations, and professional services organizations in complex civil and criminal litigation and investigations. He also counsels clients on legal ethics, Congressional investigations, District of Columbia affairs, and other issues related to state and municipal governments. He is a fellow of the American College of Trial Lawyers.

Mr. Nathan most recently served as the Attorney General for the District of Columbia from 2011 to 2014. Prior to his service as DC Attorney General, he was the General Counsel of the US House of Representatives from 2007 to 2011. Mr. Nathan served as Principal Associate Deputy Attorney General at the US Department of Justice (1993-94) and Deputy Assistant Attorney General for Enforcement in the Criminal Division (1979-81). He also served as Chair of the District of Columbia Bar Legal Ethics Committee and Vice Chair of the DC Board of Professional Responsibility which is appointed by the DC Court of Appeals to oversee the attorney disciplinary system in the District of Columbia.