By Andrew Hanson*
In his “Contract with the American Voter,” Donald Trump promised to “cancel all federal funding” to “sanctuary cities” on his first day in office. Can the federal government force states and cities to comply with its immigration enforcement agenda? It depends on how it tries to induce the state and local governments to act. While future grants of federal funding may potentially be conditioned to induce state action, it would be plainly unconstitutional for the federal government to cancel all federal funding to “sanctuary cities.”
Federal law allows the federal government to enter into agreements with state and local governments to carry out federal immigration enforcement. However, the statute explicitly states that the state and local governments are not required to enter into agreements with the federal government, and agreements are not required for state and local governments to cooperate with the federal government. Thus, state and local governments are free to choose whether to enter into an agreement or whether to cooperate with the federal government’s immigration enforcement procedures.
The cities—political subdivisions of the states—that choose not to enter an agreement or cooperate with the federal government are referred to as “sanctuary cities.” In other words, sanctuary cities are locations that have either formally or informally decided they would not assist the federal government in enforcing federal immigration laws. For example, if an unlawfully present individual is arrested for a minor offense (and it is determined they are not lawfully present in the United States), sanctuary cities will release the individual after they have resolved the state offense rather than turning them over to federal officials for immigration proceedings. Various cities throughout the country are considered sanctuary cities. It is estimated that there are more than sixty sanctuary cities, including New York, Los Angeles, and Chicago.
It is not clear how, exactly, Trump would fulfill his threats. But the details are crucial to predicting whether it would be legally permissible. His rhetoric suggests a blanket cancellation of all federal funding and presumably no future federal funding to sanctuary cities. An alternative approach could be cuts to specific programs related to law enforcement. The specific program(s) to be effected or the amount(s) of funding to be withheld has not been disclosed. Either way, cities may have valid legal challenges to defend against these threats.
As expressed recently in the Affordable Care Act case, it is well-settled law that the federal government may not commandeer the legislative processes of the states by compelling them to enact or enforce a federal program. However, there are ways for the federal government to incentivize states to act. The federal government can use the Spending Clause to grant federal funds to states and the political subdivisions of states. It can also condition those grants upon the states’ taking certain courses of action.
But this spending power has limits. Federal funding agreements are like a contract, the legitimacy of which depends on whether the sates and political subdivisions of states voluntarily and knowingly accepted the terms of the agreement. Just as changing the terms of an existing contract would be a breach of the agreement, so too would changing the terms of an existing funding agreement. Respecting this limit ensures that the federal government does not “undermine the status of the States as independent sovereigns in our federal system.” The federal government may incentivize state and local governments, but when that pressure turns into compulsion, it runs contrary to our system of federalism.
That is not to say the federal government cannot condition future funding agreements upon compliance with the Trump administration’s immigration enforcement policies. But the Trump administration is probably unable able to substantially alter existing funding arrangements (i.e., they cannot “cancel all federal funding” to sanctuary cities).
The ACA case, NFIB v. Sebelius, is complex and contains multiple holdings. Seven members of the Court agreed that the federal government could not withhold existing Medicaid funding in order to persuade states to expand the Medicaid program. In addition, Chief Justice Roberts and Justices Breyer, Kagan, Ginsburg, and Sotomayor all permitted the conditioning of future funding upon compliance with the federal government’s conditions.
To cancel all federal funding to cities, which could mean billions of dollars in some cities, seems to be more akin to the impermissible “economic dragooning” that leaves cities “with no real option but to acquiesce,” rather than the “relatively mild encouragement” that the Court has found to be permissible.
It remains to be seen whether the Trump administration will try to limit a small percentage of certain federal funding grants or pursue across-the-board cuts to penalize cities that do not fall in line. What does seem clear is that the latter approach is impermissible. Such drastic indiscriminate cuts would be devastating and likely leave them without any real option but to submit. That would be a textbook definition of intruding on our system of federalism. For a party that prides itself on being proponents of states’ rights, it seems odd for a Republican administration to also advocate for a centralized power that quashes state dissent through brute force. But, alas, everything is out of order this year, and the unexpected is truly possible.
Perhaps, with the realities of the office and the Constitution finally dawning on him, he will walk back from this stance like he has with various other campaign promises (see e.g., here and here). But with Trump, who knows?
* Andrew Hanson is a 3L at Harvard Law School.
 See 8 U.S.C. § 1357(g).
 See, e.g., Nat’l Fed’n of Indep. Bus. v. Sebelius (NFIB), 132 S. Ct. 2566, 2602 (2012); id. at 2660 (Scalia, J., dissenting); Printz v. United States, 521 U.S. 898, 933 (1997); New York v. United States, 505 U.S. 144, 161 (1992).
 See NFIB, 132 S. Ct. 2566, 2601 (2012).
 See Coll. Sav. Bank v. Fla. Prepaidpostsecondary Ed. Expense Bd., 527 U.S. 666, 686 (1999).
 NFIB, 132 S. Ct. at 2602.
 See Pennhurst State Sch. & Hosp. v. Halderman, 451 U.S. 1, 17 (1981).
 NFIB, 132 S. Ct. at 2602.
 Id. at 2607 (opinion of Roberts, C. J., joined by Breyer and Kagan, JJ.); id. at 2666 (dissenting opinion of Scalia, J., joined by Kennedy, Thomas, and Alito, JJ.).
 Id. at 2607 (opinion of Roberts, C. J., joined by Breyer and Kagan, JJ.); id. at 2642 (opinion of Ginsburg, J., joined by Sotomayor, J., concurring in part and dissenting in part).
 See NFIB, 132 S. Ct. at 2604.
 S.D. v. Dole, 483 U.S. 203, 211 (1987).