A Manhattan judge questioned on Tuesday why the NYPD abruptly ended its decades-long practice of revealing how individual police officers are disciplined for misconduct.

Joan Lobis of the state Supreme Court heard arguments Tuesday on a lawsuit asking her to force the NYPD to resume disclosing internal bulletins listing basic details of substantiated misconduct and resulting discipline. The bulletins also report promotions, changes in duty, retirements, and other personnel orders involving the department’s 36,000-officer force.

“When did it dawn on the department that they shouldn’t be releasing these orders” after four decades of doing so, asked Lobis. “It just boggles me.”

The NYPD had routinely publicized the bulletins — called orders — since the 1970s, most recently on a clipboard in the NYPD’s 13th floor press office. The department stopped last year amid a formal request for access to the orders by Legal Aid Society under the state Freedom of Information Law.

The group is suing because it wants substantiated misconduct information — available in many other states — to know more about the credibility of officers whose word is key to clients’ cases.

Lobis must decide whether New York State Civil Rights Law 50-a covers the bulletins. The statute dates to 1976, and along with California’s, is among the strictest police secrecy laws in the United States. Among other things, the law says that personnel records used to evaluate a law enforcement officer’s job performance are confidential and can only be made public with the officer’s consent or a court order.

Arguing for the Legal Aid Society, which is also pursuing similar lawsuits related to NYPD secrecy in other boroughs, staff attorney Cynthia Conti-Cook said the bulletins are exempt from secrecy because they are not the “personnel records” referenced in the law, intended to prevent harassment of cops.

“The government has not been able to point to a single case” of abuse over the course of the four decades the NYPD disclosed the bulletins.

The de Blasio administration has said it stopped the practice once it belatedly realized disclosure violated the state law, a position on which the judge repeatedly prodded the city’s lawyer, Omar Tuffaha, Tuesday.

Tuffaha, assistant corporation counsel, pointed to state higher court precedents over the years that interpret the secrecy law to cover more than just the actual personnel file.

De Blasio’s lawyers have interpreted the secrecy law more strictly than any other mayoralty in decades, though the mayor has said he wants the state to loosen the law.

“The wisdom of the legislature’s policy choice isn’t at issue in this case,” Tuffaha told Lobis.

Ben Shartsis, a lawyer with the firm of Cleary Gottlieb, which is handling the case pro bono, said the bulletins aren’t covered by the secrecy law because they’re created separate from the file and aren’t used, “to evaluate performance toward continued employment or promotion,” the language of the law.

Police forces in the area have offered various interpretations of the secrecy law. For instance, the NYPD lets the public into disciplinary hearings, but has said it won’t generally disclose the outcomes. The Nassau County Police Department has closed those hearings to the public but in the past has disclosed the outcome in at least one case.

In the recent case of Ramarley Graham, the unarmed teenager killed by an NYPD cop in 2012, the NYPD initially said the outcome of the cop’s disciplinary case would be secret, citing the 50-a law, but then changed its mind and said the family would be told.