Charter school advocates say they hope to create another eight charter schools in the state despite a law that caps the number of charters at 100.

The advocates argue that the Board of Regents, who have the power to authorize new charter schools, have misinterpreted the state charter school law.

Charter schools are public schools that operate outside most of the regulations governing other schools in exchange for increased accountability: If the schools don’t meet certain standards, their charters are revoked and the schools are closed. The Regents argue that under the state law, once a charter school closes, a new charter school cannot take its place.

“They’re flat out wrong,” the policy director for the New York Charter School Association, Peter Murphy, said, adding that the Regents’s interpretation of the law is unnecessarily strict. Mr. Murphy said the current law allows for charters that close to be reused, either by giving the charters out to new groups or restructuring the existing charter.

“There’s no reason not to have a new group come in and redesign the school,” Mr. Murphy said. “There’s absolutely nothing in the statute that forbids such a practice.”

The Daily News on Sunday reported that eight charter school slots were going unused after schools had been closed down.

A spokesman for the state Education Department, Jonathan Burman, said that the decision not to reissue charters to new schools came after careful study of the law.

“The plain and unambiguous meaning of that section of law constrains the Regents from granting any new charters once the cap of 100 has been reached,” Mr. Burman said. “The law could have been written to provide that no more than 100 charter schools can ‘operate’ at any one time, but the legislature did not choose to draft the law that way.”

Mr. Burman also said that a bill that would have changed the law to allow new charters to replace old ones failed to pass the state legislature last summer. The law would have also raised the statewide cap for charter schools to 250.

Following the defeat last summer, advocates are planning to raise the issue again this fall in the state legislature. But at least one member of the Board of Regents said she’d be open to an interpretation of the existing law that would allow new charter schools to take the place of those that have closed.

“I would do whatever we could to broaden the interpretation to increase the number of charter schools at a time when the cap has not been lifted,” said Merryl Tisch, a member of the Board of Regents. “But I’m one vote.”

Charter school opponents say the schools siphon resources away from other public schools and undermine teacher unions. Researchers have drawn conflicting results on how charter schools affect student performance, with much of the argument related to how much adjustment is made for student backgrounds. Test results released last week for the statewide reading exams showed New York City charter school students, 56% of whom were reading at or above grade level, performing slightly better on the tests than students at other public schools, 50% of whom were reading at or above grade level. Scores for three New York City charter schools have not yet been released, however, and they were not included in the average.

A spokeswoman for the Charter School Institute of the State University of New York, which also has the power to authorize new charters, Cynthia Proctor, said her agency had just begun to explore the legality of allowing new charters to open once old ones closed.

“It’s something on our radar screen, it’s something we’re thinking about,” Ms. Proctor said. “We haven’t really actively pursued it.”

Instead, she said her agency was more focused on getting the cap raised to address long waiting lists of students hoping to enroll in charter schools. Other advocates are also concentrating their efforts in an ongoing battle to raise the cap, including the New York City Department of Education.

“Opening those spots would give us eight more charters than we have now,” said David Cantor, department spokesperson. “But our charter creation goals go far beyond eight.”

Still, Mr. Murphy said he was frustrated that the Regents were effectively reducing the number of charter schools at a time when lines to get into existing schools were long.

“It certainly doesn’t benefit any children,” he said.