Trump violated the United States Constitution by directing all United States agencies to withhold funds from sanctuary cities. First, the Executive Order attempts directly to compel state and local governments to take particular actions. Second, it encourages state and local governments to fall in line by leveraging federal funds. Both mechanisms violate states’ rights that the Constitution protects.
Sanctuary cities adopted ordinances to decline to report immigration issues to federal authorities.
Generally, sanctuary cities adopt ordinances to decline to report immigrants to the Immigration and Customs Enforcement (ICE) agency. The Executive Order defines sanctuary jurisdictions as any local jurisdiction that “willfully” refuses to comply with United States Code Title 8, Section 1373.
That statute, in turn, prohibits local jurisdictions stopping “any government entity or official from sending to, or receiving from, [ICE] information regarding the citizenship or immigration status, lawful or unlawful, of any individual.” In other words, the Executive Order requires cities, counties, or other local jurisdictions to allow their officials to send to ICE information about immigrants.
The Center for Immigration Studies has generated a map of these sanctuary cities.
The Executive Order violates states’ rights by commandeering local governments.
Both Section 1373 and the Executive Order violate the Constitution by commandeering local governments. The Supreme Court has already rejected Congress’s attempts to commandeer local governments to achieve federal objectives. Although the Supremacy Clause in the Constitution makes United States law superior to state and local laws, the federalism principles inherent in the Constitution prohibit the United States from compelling state or local government action.
In the 1997 case Printz v. United States, the Supreme Court overturned a statute that required state law enforcement agents to complete background checks for gun purchasers. The Court recognized that the founding fathers did not believe the United States could direct states to hold federal prisoners. In a 1789 law, Congress requested states to assist the United States and authorized federal funds to house federal prisoners in state jails. That act compelled no state to do anything against its will.
The Supreme Court extended that non-commandeering principle to the background-check context in Printz. It rejected the proposition that Congress could direct local law enforcement officers to complete background checks. It concluded that drawing a line between the federal and state governments protected citizens and advanced liberty. “Congress cannot compel the States to enact or enforce a federal regulatory program.”
By directing states and local governments not to interfere with reporting to ICE, the Executive Order directs state actions. Thus, it violates the federalism principles and states’ rights implicit in the Constitution.
The Constitution prohibits the United States from withdrawing unrelated funding from sanctuary cities.
The Executive Order not only prohibits state and local agencies from interfering with people reporting to ICE, but also directs agencies not to provide federal funds to sanctuary jurisdictions except as the law absolutely requires. If an agency implements that direction and declines to give all federal funds to a sanctuary city, the agency would violate the Constitution.
In Chief Justice John Roberts’s initial opinion on the Affordable Care Act, the Supreme Court held that Congress may use its spending authority to “influence” states even beyond its direct powers. Nonetheless, Chief Justice Roberts explained, “when pressure turns into compulsion, the legislation runs contrary to our system of federalism.” The Supreme Court drew the line between influence and coercion by asking whether the financial incentive becomes “so coercive as to pass the point at which pressure turns into compulsion.”
The Supreme Court struck down the Affordable Care Act’s incentive for states to adopt the Medicaid provisions because it went too far. The Affordable Care Act would have withheld all Medicaid funding from the states that declined to participate. The Court concluded that incentive went too far. It found (a) that states spend on average 20 % of their budgets on Medicaid spending, and (b) that the United States reimburses states for between 50 and 83 % of those expenses. It concluded that Congress’s threat to withhold that money did more than encourage the states; the Affordable Care Act coerced states like “a gun to the head.” The Supreme Court concluded that “Congress is not free . . . penalize States that choose not to participate in that new program by taking away their existing Medicaid funding.”
The United States can condition federal funds only for related activities.
Finally, the Executive Order not only prohibits federal funding related to immigration, but also funding unrelated to immigration. The Supreme Court rejects conditions on federal grants that “if they are unrelated to the federal interest in particular national projects or programs.” Thus, the Executive Order prohibits granting federal funds to sanctuary cities regardless of their relationship to immigration.
For these three independent reasons, the Executive Order prohibiting federal agencies from providing federal funds to sanctuary cities violates states’ rights that the Constitution protects.
April 25, 2017 Update: The United States District Court for the Northern District of California indeed struck down the Order on these bases, among others.
 Executive Order: Enhancing Public Safety in the Interior of the United States (Jan. 25, 2017), available at www.whitehouse.gov/the-press-office/2017/01/25/presidential-executive-order-enhancing-public-safety-interior-united.
 Executive Order § 2(a).
 Executive Order § 9(a).
 8 U.S.C. § 1373(a).
 521 U.S. 898 (1997).
 Id. at 909.
 Id. at 921-22.
 Id. at 935.
 Nat’l Fed’n of Indep. Business v. Sebelius, 567 U.S. ___ (2012) (“Congress may tax and spend. This grant gives the Federal Government considerable influence even in areas where it cannot directly regulate.”).
 Id. (quotations omitted).
 South Dakota v. Dole, 483 U.S. 203, 207 (1987) (quotations omitted).
 Executive Order § 2(a).