Have anti-Sharia laws faced legal challenges in federal courts?

1. How the litigation began: ballot measures, model bills and a plaintiff’s challenge

The modern wave of anti‑Sharia statutes grew from model texts promoted by groups such as American Laws for American Courts and was enacted in multiple states as statutes or constitutional amendments; Oklahoma voters approved an amendment in 2010 that explicitly barred state courts from applying “Sharia law,” and that amendment was promptly challenged in federal court by Muslim plaintiffs and civil‑rights groups ^{[4] [1] [3]}.

2. Federal courts’ main legal findings against anti‑Sharia measures

Federal judges and appellate panels have repeatedly held that laws singling out Sharia raise serious First Amendment problems: courts found the Oklahoma amendment likely violated the Establishment Clause because it treated Islam as suspect and lacked any identifiable problem it was designed to remedy, a rationale that sustained injunctions and reversals in the federal courts ^{[3] [2] [5]}.

3. Why courts said those laws were unnecessary and harmful to judicial function

Beyond constitutional fault lines, federal rulings and expert commentary explained that anti‑foreign‑law bans are redundant and damaging because U.S. law already prevents enforcement of foreign or religious rules that conflict with constitutional rights or public policy; courts emphasized that preventing judges from considering international or foreign law would hamper handling of international contracts, marriages and adoptions ^{[6] [2] [5]}.

4. The competing narrative: proponents’ claims and the counter‑arguments in court papers

Supporters of these measures argued they merely prevent foreign or religious rules from undermining state law and invoked hypothetical instances of foreign‑law enforcement, but federal opinions and civil‑rights briefs found proponents could point to no real instances where Oklahoma courts had applied Sharia or international law to a harmful effect—an absence courts described as fatal to the state’s asserted justification ^{[2] [4] [3]}.

5. Litigation as politics: networks, agendas and flood of cases

Reporting and scholarship trace the anti‑Sharia push to coordinated networks that supplied copy‑and‑paste legislation and to a political strategy that often coincided with election cycles; critics and some academic analyses argue the legal campaign functions less to fix a judicial problem than to stigmatize Muslims and to translate political Islamophobia into state law—an agenda courts have taken into account in assessing intent and effect ^{[4] [7] [8]}.

6. What federal courts did not, and what remains unresolved

Federal courts have blocked specific state laws and affirmed that measures targeting Sharia raise constitutional problems, but reporting shows litigation remains politically charged and persistent: defenders of model bills continue to introduce variations that avoid explicit reference to Islam (e.g., “foreign law” language), and commentators note that while many challenges succeeded, anti‑foreign‑law proposals continue to circulate and can produce new legal skirmishes whose outcomes depend on particular text and evidentiary records ^{[4] [9] [6]}.

7. Bottom line — answer to the question

Yes: anti‑Sharia laws have not only faced legal challenges in federal court but have often been enjoined or struck down there on constitutional grounds, with federal judges concluding the measures frequently single out Islam, invent a nonexistent problem, and improperly hinder courts’ ability to apply international or contractual law ^{[3] [2] [5]}.