A major crackdown on abuses of rent-controlled and rent-stabilized apartments in New York

City could follow a ruling yesterday that allows landlords to require electronic key-cards emblazoned with tenants’ photographs – instead of old-fashioned metal keys.

Electronic keys allow landlords to try to ferret out tenants who are illegally taking advantage of below-market rents – while actually subletting their government-regulated apartments and living somewhere else. State law requires rent-regulated tenants to use their apartments as a “primary residence.”

Key-cards that track information about movements in and out of buildings have been common in commercial settings for a decade, but are not typically used in apartment buildings.

Tenant groups complain the key-cards violate privacy and could even help burglars by providing a record of their daily routines. “That information might be valuable to an outsider who could take advantage of people,” the director of the Met Housing Council, Jenny Laurie, said.

Landlords argue the cards are for security – but acknowledge that the records provide a valuable tool to enforce their rights.

“The only people who have to worry are the people trying to perpetuate some subterfuge,” a spokesman for the Rent Stabilization Association, an owners’ group, Frank Ricci, said. “I don’t think most owners care about the comings and goings of their tenants, unless they are someone who shouldn’t be there.”

The ruling that landlords can require key-cards with tenants’ photographs follows a three-year legal battle involving one of Manhattan’s largest apartment complexes.

The owners of Peter Cooper Village tried to introduce key-cards with photographs in 2003. But tenants sued in court and the case was assigned to the state’s Department of Housing and Community Renewal, which oversees the 1.04 million New York City apartments that are subject to limited rent increases each year.

An administrative law judge yesterday ruled in favor of Peter Cooper’s landlord, Metropolitan Tower Life Insurance Company. Peter Cooper Village began requiring electronic keys a year ago, but they did not include photographs and could easily be swapped among tenants, visitors, and subletters.

The lawyer representing Peter Cooper tenants, Jack Lester, said yesterday’s ruling “is big brother watching the tenants’ every movement.”

He said Met Life has not used information from the photo-less electronic keys against illegal subletters, but the records could give landlords an edge in disputes with tenants.

“It could be used to intimidate,” Mr. Lester said, vowing an appeal. “It’s the end of the beginning. We have just begun to fight.”

In addition to Peter Cooper Village, which contains about 2,500 apartments, Met Life also owns the adjacent Stuyvesant Town, which has about 8,750 apartments. The complexes, which run along First Avenue between 14th and 23rd streets, contain a large percentage of rent-regulated apartments. A lawyer representing Met Life, Daniel Ansell, declined to comment.

The local City Council member, Daniel Garodnick, a Democrat of Manhattan, denied that tenants opposed key-cards with headshots in order to protect illegal subletters. But he acknowledged that the decision could help landlords enforce the law.

“It certainly could become a tool for landlords to monitor tenants’ behavior, and to use that information against them in court,” he said.

Mr. Garodnick said he might introduce legislation requiring landlords to destroy the electronic information they obtain about tenants within a short period of time

According to a 2005 housing vacancy survey conducted by the city, rent regulated apartments account for about half the city’s rental housing stock.

Housing analysts predict yesterday’s decision could pave the way for the use of electronic keys at apartments around the city, but they said smaller buildings would likely find the systems too expensive.