Created in 1979 and added to the City Charter in 1988, the Office of Administrative Trials and Hearings hears more than 800,000 cases a year from the city's enforcement agencies. Its latest expansion came on June 13, when Mayor Bill de Blasio signed the Criminal Justice Reform Act, giving OATH jurisdiction over low-level quality of life summonses issued by the New York City Police Department and Parks Department that historically were filed in Criminal Court.

OATH's reach has grown significantly over the past 20 years. It now hears all human rights complaints under the city's Human Rights Laws (1997); claims brought by city contractors arising out of terms of their agreements (1999); single-room occupancy (SRO) landlord harassment hearings (2001); retention hearings over the police-seized vehicles allegedly used in crimes (2004); violations of the Lobbying Law (2006); and denials of marriage licenses or domestic partnerships (2008).

Also in 2008, the city's largest administrative tribunal, the Environmental Control Board, was placed under OATH. Fidel F. Del Valle said a backlog of 7,000 environmental cases was eliminated while the time it took for a decision to be issued fell from an average of 96 days in 2007 to an average of just six days in 2010 “by providing hearings and appeals online, hearings by phone and educational materials for the public,” he said. In 2011, OATH grew yet again, taking administrative cases from the Department of Health and Mental Hygiene, the Taxi and Limousine Commission and Business Integrity Commission. And just last year, OATH began hearing all Department of Consumer Affairs cases.