The outcome in the lawsuit to reclaim lost state aid for New York City schools will hinge largely on the argument of what scale of educational impact that sum could have on students.

If New York County Supreme Court Judge Manuel Mendez sides with attorney Michael Rebell, who is suing the state, he’ll agree that the lack of roughly $250 million will cause “irreparable harm” to students. If he sides with lawyers representing Gov. Andrew Cuomo and state Education Commissioner John King, he’ll concur that the total is just a fraction of what the city spends annually on education, and therefore won’t do much more than put a dent in school budgets.

Rebell filed the lawsuit earlier this month after Cuomo said he would not seek to extend a deadline that awarded increased state aid only to districts that agreed to a teacher evaluation system. New York City was one of six districts that did not meet the deadline, which Cuomo signed into law last year to force districts and their unions to negotiate the controversial plans.

The two sides were in court today for the first time arguing over Rebell’s request for Mendez to issue an preliminary injunction, an early court order that requires the defendant to either proceed or cease with a specific action. In today’s case, the state is planning to withdraw the funds and Rebell wants Mendez to prevent the state from taking back the money while he is considering the case.

To win an injunction, Rebell needs to prove some key points. First, he has to show that the state aid cut is irreparably harmful to affected schools and students while the lawsuit is pending. Second, he needs to prove a high likelihood of ultimately winning the case.

In response to the sudden funding gap, the Department of Education is planning midyear cuts for March 1, Rebell said, making an injunction especially urgent. After the hearing, Rebell said he couldn’t predict where, specifically, irreparable harm would take place.

“We don’t know that yet,” Rebell said. “You got a huge hit on the whole city so it’s going to fall out on these kids. Exactly how? Who knows, but it’s going to be devastating.”

Rebell said he left out specific evidence of harm because he believed he had a good shot at winning the case. Previous court cases firmly established that state aid disbursements were constitutionally necessary for a student to receive a “sound basic education,” he said.

Cuomo’s lawyers argued today that increased state aid — they used a larger figure, $260 million — didn’t amount to much compared to the $7.9 billion that the city received from the state this year. They said that many cuts that Mayor Michael Bloomberg and Chancellor Dennis Walcott have publicly forecast would not violate a student’s right to a “sound basic education.”

Rebell called the argument tenuous, saying that it was Cuomo who believed the amount was significant enough to dangle as an incentive for New York City and other districts to submit evaluation plans.

Arguing for the state, Assistant Attorney General Steven Schulman also said that harm from the lost aid was a relative drop in the bucket compared to what would happen if the state was unable to enforce the teacher evaluation law. Without new teacher evaluations, he said, the state would likely not be able to retain much of its $696 million Race to the Top grant. He also argued that the quality of education would suffer.

“There is no dispute here that annual performance reviews will improve education for students,” Schulman’s brief says.

In court, he said, the “grant is jeopardized by New York City’s failure to adopt a performance evaluation program.”

Mendez did not issue a ruling but told both side he would rule shortly.