Last week, Chicago filed a lawsuit against the Department of Justice for its plan to withhold police grants from cities that refuse to cooperate with immigration enforcement, sometimes known as "sanctuary" cities. The lawsuit argues that the new conditions for the Edward Byrne Memorial Justice Assistance Grant, of which the city expected $3.2 million this year, would be unconstitutional and threaten the city's ability to fight crime.

“Chicago will not let our police officers become political pawns in a debate,” Mayor Rahm Emanuel said in announcing the lawsuit. “Chicago will not let our residents have their fundamental rights isolated and violated. And Chicago will never relinquish our status as a welcoming city.”

In a press conference Wednesday in Miami-Dade County, Florida, Attorney General Jeff Session chastised Chicago city officials for not following the example of Miami, who voted to repeal their sanctuary policies.

"So if the people in Chicago and these other cities are concerned about losing money I suggest not call me," Sessions said. "Call you City Council and your mayor."

This week, the state of California announced it would file its own lawsuit along the same lines. But is it a viable argument? Chicago spoke with Northwestern law professor Nadav Shoked to find out.

Does the city have a strong case?

It's always impossible to accurately predict especially before we've seen the response from the Justice Department, but on its face, it seems like a viable claim.

What makes it viable?

The strongest argument, of many, is that the Justice Department has no power to add conditions to this specific federal grant. Congress has set specific conditions for this grant: the size of the state, or the population of the state, and the rate of violent crime, and the Justice Department is adding its own conditions that have nothing to do with the current criteria. These are called block grants, because states and cities get a block of money based on certain criteria and use it for general purposes, not necessarily guided by the federal government. The city is arguing that the executive branch is intruding in the territory of Congress.

What kind of authority does the Constitution afford the federal government to tell a city how to use those federal funds?

The city makes the argument, "The federal government cannot tell me how to run my own police." The power of policing is reserved for states, and they give that power to the cities. But this is where it gets complicated. It's not as if the Justice Department, or Jeff Sessions, gave an order to the Chicago Police Department to start arresting immigrants. He said, if you want this money, do this for me—offering an incentive to comply. The city is arguing that even just the incentive element of it, it’s also blocked by the Constitution because it is a form of interference.

I don't think that's a strong argument. In law, it's not necessarily perceived as coercion because it's not an order, it's just an incentive. Since the '80s with South Dakota v. Dole, courts have ruled that as long as it's not too coercive and as long as there is some connection between the requirement and the money—in this case there is, because it’s all about policing —it's probably fine.

San Francisco sued the administration when Trump signed his executive order  in January and has had some success in the Ninth Circuit. Is Chicago’s lawsuit similar?

The Northern California case is slightly different. They sued right after the executive order. The argument there was the executive order would withhold all funds from cities that don't cooperate with immigration officials, including funds for affordable housing, public housing, and education support. In that case, the response of the Justice Department was, Just ignore what the president was saying, he didn't mean it. We are only going to target specific grants that we have the power to withhold. The judge didn’t believe them, so that's why we see all those rulings against the federal government there.

Now, the litigation here is slightly different—on its face, the Justice Department has done what it promised the judge it would do, which is target specific grants. The problem is Congress never gave the president, or his attorney general, that power to withhold these funds. There's actually a lot of grants that give the executive a lot of discretion to give or hold funds; for example, allowing the executive branch to pick a transit program it finds most efficient and give it money. But this is not the case here.

What are the implications if Chicago is successful, or isn't successful, in this lawsuit against the Justice Department? 

Let's start with the monetary implications: They aren't dramatic. If you look at the actual amount, we are talking about money that is less than 0.03 percent of the city's budget. If the city loses this case, it's not going to abandon its sanctuary policies; it will most likely tell the federal government to keep its money.

Still, this is the first time that actual money is being withheld from sanctuary cities from this administration. This is why Chicago rushed to the courts. In a way, this is the first time you have a real lawsuit.

What happens if the Trump administration withholds funds from other programs?

If they try to go after funds for housing, education, transit, or parks—that would be a lot of money. All the major projects we've seen in Chicago in the last few years, to a great extent, have been funded with federal funds—like the 606, improvements to the L. If the federal government withholds these funds, then we're going to see many cities rushing the courts, arguing that Congress never gave the executive branch the authority to do this based on sanctuary status or immigration issues. This is when we'll see the real battle, because a lot of money will be in play.