More than 100 sanctuary cities across America received a total of $27 billion in federal funds in one year, according to a new study. President Donald Trump has promised to withhold at least some of that money if such jurisdictions don’t change their policies on illegal immigrants.

Nearly 300 jurisdictions—states, counties, or cities—have some form of sanctuary policy, meaning they limit their involvement in enforcing federal immigration law.

The new study by Open the Books focuses on federal funding provided in fiscal 2016 to 106 of the nation’s sanctuary cities, not including state or county policies.

The study attempts to show the fiscal risk to cities if they continue to protect illegal immigrants from deportation or other action by authorities, despite Trump’s recent executive order vowing to punish them.

“When the order was issued, people didn’t know what was at stake,” Adam Andrzejewski, the founder and CEO of Open the Books and author of the study, said in an interview with The Daily Signal. “Our study found the entire universe of money at stake is up to $27 billion. The courts will rule what types of funding [for sanctuary cities] can constitutionally be withheld, but it’s an open question right now.”

Open the Books, a nonprofit, describes its mission as revealing public spending records to the public.

According to the study, $16 billion in federal funds went to 12 cities where 1 in 5 illegal immigrants live.

Of those cities, New York City received the most grant funding, with $7.6 billion. Chicago is next with $5.3 billion.

The study also provides some details on categories of federal grants and direct payments to each of the 106 cities it covers.

Trump Cites ‘Immeasurable Harm’

Andrzejewski acknowledged that his study is limited because Trump, in his Jan. 25 executive order, did not specify what types of funding the executive branch would withhold from sanctuary cities.

The executive order directs the attorney general and the secretary of the Department of Homeland Security to identify sanctuary cities, or jurisdictions, that the government should target to withhold “federal funds, except as mandated by law.”

“These jurisdictions have caused immeasurable harm to the American people and to the very fabric of our Republic,” Trump’s executive order said.

Legal and immigration experts say they doubt Trump can eliminate all federal funding from sanctuary cities, citing a Supreme Court ruling that the government only can withhold funding to localities if the money is relevant “to the federal interest in the project.”

The amount of money withheld also matters.

The Supreme Court has said the blocked funding cannot amount to “a gun to the head,” meaning a substantial percentage — about 20 percent — of a state’s budget.

Cities, counties, and states with sanctuary policies get federal money for dozens of departments and agencies, most of which are not related to immigration or law enforcement.

“If Trump’s order is looking at every penny a jurisdiction gets, the further you get away from the law enforcement area, the less likely it is a judge would consider that withholding the funding is OK,” Theresa Cardinal Brown, director of immigration policy at the Bipartisan Policy Center and a former policy adviser at the Department of Homeland Security, said in an interview with The Daily Signal.

Experts agree that certain grants distributed by the Department of Justice and Department of Homeland Security could be withheld from sanctuary cities.

One potential target, according to USA Today, is the Justice Department’s State Criminal Alien Assistance Program, or SCAAP, which distributed $165 million in 2015 to local agencies that detained illegal immigrants in their jails.

‘No Clear Guidance’

Laurie Robinson, a former assistant attorney general under Presidents Bill Clinton and Barack Obama who led the Office of Justice Programs, said the attorney general has broad authority and could cut off funding for programs addressing drug addiction, domestic violence, and violence against women.

“The authority, the way it’s written in the law, is very vague,” Robinson told The Daily Signal in an interview. “For example, one open question is could the attorney general block research grants for criminal justice purposes that go to universities and think tanks. If I were the recipient of research grants, I would be concerned, because there’s no clear guidance.”

In May, the Obama administration’s Justice Department undertook a review on whether to withhold law enforcement money from 10 sanctuary cities, including New York, Chicago, and Philadelphia.

The administration sent letters to those jurisdictions, asking them to certify that they comply with a federal law requiring local governments to share certain information about illegal immigrants with federal officials.

The law in question states that jurisdictions cannot prohibit sharing information about “the citizenship or immigration status, lawful or unlawful, of any individual.”

Trump’s executive order states that the government will use this standard to determine whether a state, city, or county is a sanctuary that should lose funding.

Action at the State Level

As the Trump administration decides which cities and kinds of funding to target, at least one state is moving forward with cutting aid to a sanctuary jurisdiction.

Texas Gov. Greg Abbott, a Republican, on Wednesday cut a $1.8 million grant for criminal justice programs to Travis County, which includes the state’s capital city, Austin.

Abbott’s decision to block the grant funding came on the same day newly elected Travis County Sheriff Sally Hernandez planned to implement a policy limiting cooperation with federal immigration authorities in certain circumstances.

Austin ranks No. 5 on Open the Books’ list of 12 cities by estimated population of illegal immigrants.

On Tuesday, San Francisco became the first city in the country to sue Trump over his order to withhold federal funding, saying it is unconstitutional.

“You can’t put a gun to the head of states and localities to get them to comply with what you might want at the federal level,” City Attorney Dennis Herrera said.

‘There Will Be Lawsuits’

Supporters of sanctuary policies say they create trust between police and immigrants. They argue that local jurisdictions are not required by law to help enforce federal immigration law.

Under a 2014 federal appeals court ruling, cooperating with federal immigration requests is voluntary for local jurisdictions, and they are legally free to enact their own policies.

San Francisco became the launching pad for the national debate over sanctuary cities in 2015 after Kathryn Steinle, 32, was shot and killed on a popular city pier by an illegal immigrant with a criminal record who had been deported at least five times.

Open the Books reported that San Francisco, No. 10 on its list by estimated illegal immigrant population, received about $509 million in federal funds for fiscal year 2016.

Cardinal Brown, of the Bipartisan Policy Center, said she expects the courts to have a major say on how fights between states or cities and the federal government play out.

“It is a 100 percent guarantee there will be lawsuits, and a lot of those questions over funding will be decided in court,” she said.