Justice Reform

The administration of Mayor Bill de Blasio has steadily expanded the city’s interpretation of a state law that bars public disclosure of the personnel records of police officers, firefighters and corrections officers.

The Legal Aid Society launched a broadside Monday at the state’s familial DNA testing proposal, saying the move is an abuse of power.

It is one of law enforcement’s most expansive powers: If the authorities believe that someone has knowledge of a crime, they can — under threat of arrest — force the person to testify in court by obtaining what is known as a material witness warrant.