Mount Vernon Mayor Richard Thomas filed a lawsuit Thursday against the City Council.
The suit accused the council of overstepping its boundaries and asked a state Supreme Court judge to block it from sending out municipal checks without mayoral permission.
Thomas also sought to block the council from trying to terminate some of his employees in a dispute over their residency status.
The judge ruled in his favor and ordered the council to temporarily cease its actions.
Members say they believe the lawsuit has made the strained relationship between City Council and the mayor even worse.
One longtime observer of the city's politics tells News 12 that the lawsuit will cost taxpayers hundreds of thousands of dollars.