The suit is part of a larger public outcry against the NYPD, which is also under fire for its surveillance of American Muslims, its dealings with Occupy Wall Street protesters, and its increasingly frequent practice of stopping and frisking black and Latino men. But few have pointed to the thick information wall surrounding Operation Clean Halls, which has been in existence, in some form, since 1991.

"The NYPD and New York City in general under [Mayor Michael] Bloomberg operate on the premise that data is power," said Donna Lieberman, executive director at the New York Civil Liberties Union. "They claim to develop public policy based on 'The facts, ma'am, and only the facts.' At the same time, they are as stingy as stingy can be about giving out the facts, which they and only they have."

Clean Halls, also known as the Trespass Affidavit Program, began in Manhattan under Mayor David Dinkins' administration, a time when New York faced widespread homelessness, a faltering economy, and a crack-fueled crime wave. While Dinkins was often criticized during his administration, today he is credited with setting in motion a series of policies that began to turn the city around -- including the hiring of thousands of new police officers.

Clean Halls was one of his programs for buckling down on crime. To enroll, the police department asks landlords to sign an affidavit, permitting officers to enter a private building at any time and question and arrest unlawful loiterers. Building owners provide the police with a tenant roster, and anyone not on that roster, or who cannot give a reasonable explanation for presence in the building, is subject to arrest.

The program later expanded into all five boroughs, but it's unclear how fast it spread or how many landlords enrolled their buildings. The lawsuit's text says there are 3,895 Clean Halls participants in Manhattan, and nearly every building in the Bronx is enrolled. But the NYPD will not release the list of residences registered for the program, saying the release of this data would constitute an unwarranted invasion of landlords' personal privacy.

The NYCLU is embroiled in a separate lawsuit with the police department to obtain that information.

New York also allows the police to conduct patrols inside city-owned public housing buildings, as do many other cities across the nation. In New York, though, patrols of public buildings are subject to a level of transparency and regulation that the police department has not extended to private Clean Halls buildings. A list of all public housing residences is available online, for example. And in 2010, the police department amended the code of conduct for patrolling inside public buildings, amid complaints of baseless stops and arrests.

Critics of Clean Halls argue that while the program may have legitimate crime-fighting origins, the opaqueness surrounding it has allowed the program to expand unchecked. "I want the police to be involved," said Jacqueline Yates, a 53-year-old former correctional officer and resident of a Clean Halls building in the Bronx. "We need them, there is no doubt about that. It's the way they go about policing."