The United Federation of Teachers filed suit Monday against the Department of Education over its plans to close 19 city schools.
The suit accuses Schools Chancellor Joel Klein of ignoring the law and not properly analyzing the impact of closures on students and communities.
UFT President Michael Mulgrew was joined by teachers, parents, community groups and elected officials for the announcement.
"It has become clear to us that they have not followed the law," Mulgrew argued.
The Panel for Education Policy voted last week to close 19 underperforming schools.
The decision came against objections from students and parents, who rallied and spoke at the meeting for nine hours.
"We listened. I mean we did detailed analysis of these schools and we listened to what people had to stay, but at the same time we cannot allow schools that have not done their job, so we met the letter of the law," said Deputy Mayor Dennis Walcott.
"What we are asking here is for this process to be redone, because it was not followed correctly. We cannot ignore the public comment," Mulgrew said.
During an appearance Monday on NY1's "Inside City Hall," Klein responded strongly to the lawsuit.
"The schools that were front and center in that lawsuit like Jamaica, Beach Channel and Columbus and others, they were schools that were identified by the state as persistently lowest performing in the entire state. What we need to do is come up with better solutions for our state," Klein said.
When asked about accusations that the process was fixed, Klein said that during the public hearings, no one made a compelling case for keeping the schools open.
The schools will be phased out over several years, meaning current students will be allowed to graduate, but there will be no new enrollments.
Most of the closed schools will be replaced by smaller schools, often in the same building.