A native of New Jersey, Todd G. Monahan graduated from Rutgers University in 1999, and received his J.D. from Albany Law School in 2002, where he served as an Executive Editor on the Albany Law Review. He was admitted to the state bars of New Jersey and New York in 2002, and is also admitted to practice in U.S. District Court for the Northern District of New York and the District of New Jersey, as well as the U.S. Court of Appeals for the Second Circuit and all military courts.

In over 5 years on active duty in the U.S. Marine Corps, Todd held positions of Legal Assistance Officer, Defense Counsel, Civil and Operational Law Officer, and Deputy Staff Judge Advocate for 2 major commands. In 2004-2005, Todd served as the Legal Liaison Officer between the Central Criminal Court of Iraq and the First Marine Expeditionary Force at Camp Fallujah, Abu Ghraib Prison, and the U.S. Embassy in Baghdad, Iraq, training field units in detainee processing and evidence collection, recommending prosecution or release of detainees, and coordinating prosecution efforts with Iraqi officials. In 2007-2008, Todd held the post of Special Assistant U.S. Attorney for his installation, Marine Corps Air Station Cherry Point, North Carolina, responsible for prosecuting civilian offenders in U.S. District Court for the Eastern District of North Carolina.

Todd returned to civilian practice in New York's Capital District in March 2008.