New York has staked new ground in the national battle over barring illegal immigrants from having driver’s licenses, with the City Council this week urging the state to opt out of a new federal law.

In May of this year the Real ID Act, as part of a must-pass war appropriations bill, created federal provisions for driver’s licenses based on legal status and gave states three years to comply.

The City Council, in the first resolution of its kind, urged the New York State Legislature to opt out on Wednesday, citing the costs of implementing the bill and the burdens it would place on immigrants. The National Conference of State Legislatures, which vocally has opposed the law, has estimated that the Real ID Act will cost $500 million to $700 million over five years to implement.

The chairman of the council’s committee on immigration, Kendall Stewart, said the law would unjustly catch in its dragnet immigrants who do have legal status, barring them from having licenses.

Moreover, he said, it is better for New York to let undocumented immigrants drive. A few years ago, the state began a crack down on illegal immigrants driving with fraudulent Social Security numbers, by checking the numbers against a national database. This is among the requirements that the Real ID Act would mandate.

“The cost is not only to the folks who consider themselves undocumented, but to the city itself,” Mr. Stewart said. “People who’ve had a driver’s license for years are getting denied their licenses.”

While other states have framed the argument over the Real ID Act as a financial or states’ rights issue, in New York the ideological arguments have run strong because while New York strongly supports immigrant rights, it also is acutely aware of the threat from terrorists.

Amanda Bowman, the president of the Coalition for a Secure Driver’s License, a New York-based group that was one of the principal advocates for the Real ID Act, said the license provisions are simply about verifying identity. “We know how important this is because 15 of the 19 terrorists had multiple licenses, and it was these licenses which enabled them to board the planes on 9/11,” Ms. Bowman wrote in an e-mail. “New York’s license is now a model for the rest of the nation – and it needs to stay that way – as we remain the city and population at greatest risk from a terrorist attack.”

Ms. Bowman’s group recently launched a campaign to urge other states voicing opposition to the Real ID Act to adopt the measures. New Mexico, one of the states where the group has targeted its efforts, is one of 11 states that do not require residents to prove legal residence. The state’s governor, Bill Richardson, has said that by allowing illegal immigrants to receive licenses, the number of uninsured drivers has plummeted, and the state has become safer because law enforcement officers are better able to locate undocumented immigrants.

New York’s Department of Motor Vehicles would be well advised to follow New Mexico’s lead, an attorney with the National Employment Law Project, Amy Sugimori, said. “The net impact isn’t going to be that people really feel safer, it’s going to be that they’re inconvenienced and resources are diverted,” Ms. Sugimori, who is also a member of the New York Coalition for Immigrants’ Rights to Driver’s Licenses, said. “This is a way, starting at the city level, for states to say we don’t think this is a good idea, we really want to voice our opposition.”

The Department of Homeland Security is still negotiating the regulations of the law. A spokesman for the New York Department of Motor Vehicles, Ken Brown, said, “We’ll continue to work to reach an appropriate balance that protects the rights of individuals and ensures the security of all New Yorkers.”