This article is more than 3 years old

This article is more than 3 years old

San Francisco filed suit against Donald Trump on Tuesday, becoming the first city to bring a legal challenge against the president’s executive order targeting sanctuary cities.

“The president’s executive order is not only unconstitutional, it’s un-American,” said Dennis Herrera, the city attorney.

On 25 January, Trump signed an executive order mandating that the federal government withhold grants from localities that limit cooperation with federal immigration enforcement – a practice known as “sanctuary”. The order also directs the attorney general to explore “appropriate enforcement action” against local government agencies following sanctuary policies.

Thirty-nine cities, 364 counties and four states have some kind of sanctuary policies in place, according to an analysis by the Immigrant Legal Resource Center.

Citing the 10th amendment of the US constitution, which delegates powers not granted to the federal government to states and the people, the lawsuit alleges that the order is “a severe invasion of San Francisco’s sovereignty”. The suit also accuses the president of acting “in blatant disregard of the law”.

“You’re not an emperor who rules by fiat,” Herrera said at a news conference, describing the message he wants to send to Trump. “Obey the rule of law.”

The suit seeks to prevent the federal government from blocking funds to San Francisco. Herrera estimated that the city had about $1.2bn in federal funding at stake.

The White House and the US attorney general did not immediately respond to a request for comment.

Proponents of sanctuary policies, including Herrera and San Francisco’s mayor, Ed Lee, who also attended the press conference, argue that they make cities safer by enabling undocumented immigrants to seek help from law enforcement or local agencies without fear of deportation.

A study by the Center for American Progress found that there were on average 35.5 fewer crimes committed per 10,000 people in sanctuary counties than in non-sanctuary counties.

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Sanctuary policies became a major flashpoint in the presidential campaign when a 32-year-old woman, Kathryn Steinle, was randomly shot and killed by an undocumented immigrant in San Francisco. The shooter, Juan Francisco Sanchez-Lopez, had recently been released from a San Francisco jail despite a request from federal immigration authorities, who sought to deport him.

Steinle became a key talking point for Trump, who said that her death was “yet another example of why we must secure our border immediately”.

On Friday, Miami-Dade County became the first jurisdiction to back down on sanctuary policies, with Mayor Carlos Gimenez announcing that the county would “fully cooperate” with Trump’s order. But other cities around the country have been gearing up for a fight with the Trump administration over immigration policy.

It was with that defiant tone that Lee addressed the new lawsuit, saying: “Today, we fight back.”