The union representing San Francisco police filed an unfair labor practices lawsuit against the city this week over a use of force policy that prohibits officers from firing at moving vehicles and putting people in chokeholds.

The lawsuit was filed in Superior Court Tuesday by the San Francisco Police Officers Association. It seeks to block the city from implementing the new policy, which was approved by the Police Commission Wednesday night, and force it back into arbitration or negotiations with the union.

“We’re a labor union and our members have a right to negotiate over working conditions,” union president Martin Halloran said in a statement about the group's 2,300 police officers. “The Commission wants to ignore those labor rights. The Charter is clear that our dispute must go to arbitration, so we’re asking a judge to order the Commission back to the table.”

The union alleges the city's Police Commission prematurely declared an impasse in negotiations in October and has refused to bargain further on the issue of whether officers can fire at moving vehicles.

The lawsuit claims that city negotiators made verbal agreements to allow shooting at vehicles in exceptional circumstances such as terrorist attacks where vehicles are being used as weapons, but then refused to put those agreements in writing. Halloran deemed this move "bad faith" bargaining.

The commission also reneged on an agreement to allow the use of a control hold known as the carotid restraint, according to the lawsuit.

The policy bans the use of chokeholds but police had argued that the carotid restraint, a type of control hold that stops blood flow to the brain, could be used safely with proper training and was invaluable for smaller officers seeking to subdue a larger suspect.

"We're asking a court to intervene and force the Police Commission back to the negotiating table," Halloran said. "The Commission tells us one thing in closed door meetings, then they refuse to put it in writing. They sign agreements on one day, and renege on them the next."

Union leaders say officers and the public will be put at risk by the new use of force policy, which is getting the cold shoulder from the rank and file. The rule may lead to deadly results, with officers being forced to use more lethal options in certain situations.

"We will seek a judge's approval to force the department to not to implement the policy until we either get back to the negotiation table or we let a judge decide or let an arbitrator decide," Halloran insisted.

The commission debated a motion Wednesday night to allow the use of carotid restraints in certain circumstances, at least until other unspecified alternatives could be made available to officers. However, that motion was defeated in a 4-3 vote.

Commission president Suzy Loftus said that while the union had sought an exception to the ban on shooting at moving vehicles for situations where vehicles were used as weapons, past experience had demonstrated that this approach backfired.

After former police Chief Greg Suhr introduced a ban on shooting at moving vehicles in 2011 that included a list of exceptions, such incidents had actually increased, Loftus noted.

Instead, Loftus introduced language intended to make it clear that incidents would be reviewed on a case-by-case basis.

"There is a strict ban in this policy on shooting at cars and there is also an awareness that we cannot predict every situation that officers may face," she said.

The ban on shooting at moving vehicles and on carotid restraints are both backed by the U.S. Department of Justice, and are just two of 272 new reforms passed by the commission on Tuesday night.

The city entered into a collaborative review process with the Department of Justice early last year that resulted in a report released in October with 479 recommendations for reforming the San Francisco Police Department.

The union is also pushing for the city to allow the use of Taser stun guns to provide an additional less-lethal option for officers. That proposal has been repeatedly shot down in the past in the face of intense community opposition, and Halloran on Thursday said the commission has refused recently to even discuss it.

The police commission as a group is not commenting on the lawsuit, but one commissioner told NBC Bay Area that the new policies will go into effect immediately - even the two that are most contentious with officers and the union.

"The use of choke holds is banned, shooting at cars is banned,” said San Francisco Police Commissioner Joseph Marshall.

Mayor Ed Lee issued a statement saying that the city is committed to implementing the new reforms and will continue to work with the everyone involved to ensure public safety and restore trust in the police department.