CHICAGO (AP) — Mayor Rahm Emanuel has taken his fight against President Donald Trump’s immigration policies to court, with Chicago becoming one of the first cities Monday to sue over what many U.S. cities argue are illegal bids to withhold public safety grants from so-called sanctuary cities.

A 46-page lawsuit against the government was filed in U.S. District Court in Chicago a day after Emanuel announced the litigation and said the city won’t “be blackmailed” into changing its values as a city welcoming of immigrants.

It’s the latest round in a battle pitting several U.S. cities against the Trump administration. The cities have opted to limit cooperation with government enforcement of immigration law while federal officials threaten to withhold funding if those cities don’t comply.

A first order of business now that Chicago’s suit has been filed will be to ask a judge to put a freeze on the policy as the civil case plays out, said Edward Siskel, the head of City Hall’s legal department. That request for a preliminary injunction could be made within days.

Chicago has received the grant funds at the heart of the lawsuit since 2005. It spent $33 million in grants to buy nearly 1,000 police cars in that 12-year period; it got $2.3 million last year. In addition to cars, funds were also used for radios and SWAT equipment.