Occupy demonstrators and the National Lawyers Guild announced on Monday that an injunction was filed in federal court, asking to preserve the status quo.
Their argument is that the City Council passed a resolution allowing them to stay at City Hall.
"The mayor cannot unilaterally decide to withdraw that permission," said Mario Brieto of Occupy L.A. "It has to go back to a full City Council and the full City Council has to go on record saying that they want to withdraw that permission to be on the city lawn."
Attorneys with the nonprfit organization said they don't expect to see any response from the federal court until at least Wednesday, but filing alone should be enough to keep the city from rousting them in the near term.
"I would frankly be surprised if the police under these circumstances and given the tolerance they've shown so far were to move in on this occupation before the court has had a chance to rule," said James Lafferty, executive director of the National Lawyers Guild of Los Angeles.
Protesters declared victory after police withdrew from their encampment outside City Hall. Officers cleared the streets, but did not dismantle the tent city.
"This is the largest Occupy camp that's still standing in the United States, and I think last night, the show of solidarity, the show of love and compassion with the city of L.A. was really a win for all of humanity," said one unidentified Occupy protester.
Mayor Antonio Villaraigosa had set 12:01 a.m. Monday as the deadline for the protesters to begin moving out, but the deadline came and went.
Los Angeles was on a citywide tactical alert as police moved into the area around 12:15 a.m. When protesters spilled out onto downtown streets, police were forced to call for back-up.
"I had to bring in resources from all over the city," said Police Chief Charlie Beck, calling it a drain of city resources.
Officials said they had no plans to raid the encampment. Their first priority was to clear the streets before the morning rush hour.
"We, at that time, just decided that it wasn't the right time for us to go in and move everybody," said Cmdr. Andrew Smith. "We wanted to give everybody ample opportunity to get out of the tents."
The protest was mostly peaceful, but some people were seen throwing sticks and bottles at police officers. At least four protesters were arrested.
Surface streets around City Hall were closed for several hours as police moved demonstrators onto the sidewalks. Protesters were allowed to return to their camps, but police say they will be asked to move at some point. The LAPD has not yet set a timeline for when that will happen.
"My concern is that we do it at the proper time. We do it when it is the safest for my officers, when it is the safest for the people in the park, and that we do it with as little drama as possible," Beck said.
The protesters and about 485 tents have been on the City Hall lawn for about two months. Some protesters began packing up on Monday, but others said they plan on staying.
Some Occupy L.A. protesters said they'll be moving to the Ports of Los Angeles Dec. 12.