Tenant groups said the law had been ineffective because the cases were hard to prove and because, if they lost, tenants could have to pay the landlord’s legal fees.

In a case settled in December, the state accused Castellan NYC Partners and Liberty Place Property Management of offering sums as low as $2,000 to get mostly Spanish-speaking immigrants to waive their tenancy rights in buildings in Brooklyn, the South Bronx and the Harlem and Washington Heights sections of Manhattan. In one federal court case, a group of black tenants in a Flatbush development, Homewood Gardens Estates, said they were offered $4,000 to $15,000 to leave their apartments as part of a harassment campaign that included landlords’ refusals to do repairs.

“Our clients rarely have the resources to find other affordable apartments,” said Edward Josephson, director of litigation for Legal Services NYC, which filed the federal lawsuit in April.

Jacob Laufer, the lawyer for Homewood Gardens Estates, said his client “categorically denies harassing tenants.” But Mr. Laufer, citing the pending litigation, declined to answer questions.

For tenants who decide to stay, even an offer of $100,000 loses appeal when measured against the realities of the real estate market.

Ms. Ng and her husband, a 61-year-old bus driver for the city who spoke on the condition that his name not be used because he feared it would jeopardize his job, said they subtracted taxes, moving costs and other expenses from the offer amount. Then they calculated how long the money would last if they rented another apartment for about $2,000 a month. “In two and a half years all the money would be gone,” he said.