Resource: Chamber of Commerce of the United States v. Whiting

The provision of the Legal Arizona Workers Act that provides for the suspension and/or revocation of the business licenses of Arizona employers who knowingly or intentionally employ unauthorized aliens is not expressly preempted by the federal Immigration Reform and Control Act, which prohibits the knowing hiring of unauthorized immigrants and preempts state laws imposing sanctions on those who hire unauthorized immigrants; the Arizona law falls within the IRCA's exception that preserves state authority to impose sanctions through licensing and similar laws. Nor is Arizona's requirement that employers use the federal E-Verify system to confirm eligibility for employment not impliedly preempted, as it does not conflict with the federal scheme, and the federal statute establishing E-Verify does not constrain state action.