On March 3, 2020, the United States Supreme Court held in Kansas v. Garcia that federal immigration law did not preempt Kansas from prosecuting aliens for supplying false information on tax-withholding forms even though state law may not criminalize the use of the same false information on federal I-9 employment-verification forms. The federal government supported Kansas’ position in the case. In a 5-4 decision, the Supreme Court sided with Kansas and the United States, and held that the federal Immigration Reform and Control Act of 1986 (IRCA) does not preempt state identify-theft and false-information statutes as applied to aliens who use others’ Social Security numbers on tax-withholding forms.  

The case addressed both express and implied preemption under the Constitution’s Supremacy Clause. For present purposes, the most important ruling concerned implied “conflict” preemption, that is, the principle that state laws are preempted when they stand as an obstacle to congressional purposes in federal law. The majority took a narrow, textual view of conflict preemption, with two of the five justices in the majority calling for abrogation of the doctrine entirely.