It argues that the executive order, which allows Immigration and Customs Enforcement and other federal agencies to maintain office space at the jail, violates the city's prohibition on public officials using their office for personal benefit.
In an emailed statement, mayoral spokesperson Kayla Mamelak Altus said the city would review the council’s lawsuit. She added that it “seems baseless and contrary to the public interest in protecting New Yorkers from violent criminals.”
Adams has repeatedly denied making any deal with the Trump administration over the criminal case.
ICE agents previously had a presence on the Rikers Island facility, which is on a hard-to-reach island in the East River, but they were effectively banned from operating there in 2014 under New York City's sanctuary laws.
In December last year, Adams told Fox News after a meeting with President Donald Trump's border czar Tom Homan that Homan would like access to Rikers, and his administration was looking into "exceptions" to the sanctuary law.
In February, following another meeting with Homan, Adams announced he would once again allow ICE agents in the jail complex to assist with gang and drug-related investigations.
The meeting came days after the Justice Department had ordered federal prosecutors in Manhattan to dismiss Adams' charges. The following day, the request was made to a federal court, a move that immigrant rights groups and Adams' critics immediately cast as a quid pro quo.
Adams announced he would deputize his first deputy mayor, Randy Mastro, to handle all decision-making around the return of ICE to Rikers Island, in order to “ensure there was never even the appearance of any conflict.”
As a result, the April 8 executive order authorizing ICE's return to Rikers Island was signed by Mastro, rather than Adams.
In their lawsuit, the City Council members said that delegation was both unlawful and unprecedented.
“No mayor has ever delegated executive order powers, and no executive order has been signed by anyone but the mayor,” the complaint states.
Adams, a Democrat running for reelection as an independent, has increasingly warmed to Trump since November, riling critics who say he should be doing more to block the administration's crackdown on immigrants.
Among the many candidates seeking to replace him as mayor in the upcoming election is Adrienne Adams, the current speaker of the City Council.
“The mayor has compromised our city’s sovereignty and is now threatening the safety of all New Yorkers, which is why we are filing this lawsuit to halt his illegal order that he shamelessly previewed on the Fox News couch with Tom Homan,” Adrienne Adams said in a statement Tuesday. “When New Yorkers are afraid of cooperating with our city’s own police and discouraged from reporting crime and seeking help, it makes everyone in our city less safe.”