The Police Benevolent Association filed the suit in Staten Island Supreme Court and plans to file a request for a temporary injunction preventing the city from imposing the mandate while the lawsuit is pending.
The move came after Mayor Bill de Blasio announced last week that all city workers would be required to get vaccinated or be placed on unpaid leave or terminated after the Oct. 29 deadline. There is no option to undergo weekly COVID-19 testing.
The PBA said the mandate violates its members' right to make their own medical decisions.
"The Vaccine Mandate will impose irreparable harm on police officers. A police officer with sincerely held medical, health, or religious concerns with the vaccine will face irreparable harm if forced to submit to vaccination prior to the Court’s determination whether a the Vaccine Mandate is unlawful," the lawsuit states. "These officers have rights to medical autonomy and religious observance that would be violated by forcing them to submit to a vaccination. Once a vaccination occurs, that bell cannot be un-rung."
Nearly 70% of New York Police Department employees are vaccinated while more than 60 employees have died from COVID-19.
On Monday, de Blasio said the requirement will most likely increase vaccination rates.
"We've seen the mandates move a lot more people to get vaccinated," he said.
The mayor got vaccinated in March but received a Moderna booster shot Monday during his press briefing. Nearly 12 million doses have been administered citywide, he said. Fox News has reached out to his office.
In a letter to members on Monday, the PBA said NYPD leaders have not given specifics on the implementation of the mandate.
"The universal response has been that they are waiting to hear from City Hall," the letter said. "Once again, it is clear that the NYPD is being run directly by Mayor de Blasio and his advisors, who care more about politics than public health or public safety."
"NYPD members are frustrated because we are trying to make important, possibly life-changing decisions while our leaders keep us in the dark – perhaps intentionally," the union added.
Other unions have sued the city over the vaccine mandate. Earlier this month, a judge declined to grant a temporary injunction requested by teachers and staff of the Department of Education over a mandate provision.
Protesters marched in support of Brooklyn Nets superstar Kyrie Irving’s public opposition to the vaccine. The team has barred him from practice and playing until he gets vaccinated.
Many supporters marched to the Barclays Center and tried storming the doors to the arena.