Which court rulings have most constrained state laws banning sanctuary policies since 2017?
Executive summary
Since 2017 the most consequential court rulings constraining federal attempts to punish sanctuary jurisdictions have not struck down sanctuary laws themselves but have limited the federal government’s ability to coerce states and localities—principally via the anti‑commandeering doctrine (Murphy) and a string of federal appellate decisions that blocked or narrowed federal conditions on grants tied to immigration cooperation (San Francisco v. Trump and companion cases) [1] [2] [3]. At the same time, circuit splits—most notably the Second and Fifth Circuits—have left parts of the legal field open to future federal challenge, producing a fractured map rather than a single national rule [3] [4].
1. Murphy v. NCAA: the doctrinal foundation that hamstrung federal coercion
The Supreme Court’s decision in Murphy v. NCAA reaffirmed and sharpened the anti‑commandeering rule—holding that the federal government cannot issue direct commands to states to enact or administer federal regulatory programs—and courts have invoked that logic to reject federal efforts to compel local participation in immigration enforcement [1] [5]. Legal scholars and state litigants quickly cited Murphy to undermine federal grant‑conditioning strategies and statutes alleged to force state action on immigration, framing the issue as one of federalism rather than simple preemption [1] [6].
2. San Francisco v. Trump and the Ninth Circuit: blocking funding threats
Litigation brought by San Francisco, Santa Clara County and other jurisdictions produced district and Ninth Circuit rulings that prevented the administration from withholding federal law‑enforcement grants on the basis of sanctuary policies and invalidated parts of the January 2017 executive order as an unconstitutional spending‑clause and separation‑of‑powers intrusion [2] [3]. Judge William Orrick’s nationwide injunction and subsequent Ninth Circuit summary judgment victories established a practical bar on broad, unconditional funding cuts tied to local noncooperation, a line courts said Congress had not drawn when it authorized the grants [3] [2].
3. Circuit splits: Second Circuit, Fifth Circuit and the fractured landscape
The nationwide picture is anything but settled: while the Ninth Circuit and several district courts sided with sanctuary jurisdictions, the Second Circuit in State of New York v. DOJ reached a different conclusion in 2020, upholding certain federal conditions, and the Fifth Circuit has upheld Texas’s SB4 against First Amendment challenges—decisions that demonstrate a split among appellate courts and leave ultimate resolution to the Supreme Court or shifting political branches [3] [4]. These divergent rulings mean sanctuary laws remain legally secure in some regions but vulnerable in others, depending on the controlling circuit precedent [3] [7].
4. Statutory fights over §1373, §1324 and detainers: narrowings not eliminations
Courts confronting federal statutes and DOJ letters tied to §1373 and criminal statutes like §1324 have often read federal law narrowly or found the federal government overreached; several courts judged §1373 challenges through anti‑commandeering and spending‑clause lenses and refused to allow wholesale federal conditioning of grants, while the Ninth Circuit has required specific intent elements to apply §1324 criminally—both trends that blunt federal threats but do not categorically immunize all local noncooperation [8] [9] [6]. Lower courts have also held that honoring ICE detainers can create Fourth Amendment liability for jurisdictions that hold people without warrant, reinforcing legal risk calculations that underpin sanctuary policies [8].
5. What those rulings mean in practice—and what remains unresolved
Collectively, the post‑2017 decisions have constrained the federal government from easily weaponizing grant money or blunt executive‑order mandates to nullify sanctuary policies, instead forcing litigation under anti‑commandeering, spending‑clause and preemption doctrines that favor local autonomy in many circuits [2] [3] [1]. That said, circuit splits and recent renewed federal litigation mean the legal limits are provisional: the Supreme Court has not issued a definitive, nationwide ruling resolving tensions among plenary federal immigration power, the anti‑commandeering rule, and Congress’s spending authority—so sanctuary laws are protected in some places but remain contestable in others [10] [3] [11].