Kansas (P) law makes it a crime to commit “identity theft” or engage in fraud to obtain a benefit. P's identity-theft statute criminalizes the “using” of any “personal identifying information” belonging to another person with the intent to “defraud that person, or anyone else, in order to receive any benefit.” Ds are aliens who are not authorized to work in this country but nevertheless secured employment by using the identity of other persons on the I-9 forms that they completed when they applied for work. They also used these same false identities when they completed their W-4s and K-4s. Ds were convicted under P's for fraudulently using another person’s Social Security number on tax-withholding forms. In all three cases, Ds argued before trial that IRCA preempted their prosecutions. They relied on 8 U. S. C. §1324a(b)(5), which, as noted, provides that I-9 forms and “any information contained in or appended to such form[s] may not be used for purposes other than for enforcement of ” the INA or other listed federal statutes. P dismissed the charges that were based on I-9s and agreed not to rely on the I-9s at trial. P maintained that §1324a(b)(5) did not apply to Ds’ use of false Social Security numbers on the tax-withholding forms. Ds were convicted and the court of appeals affirmed. The Kansas Supreme Court reversed, concluding that “the plain and unambiguous language of 8 U. S. C. §1324a(b)(5)” expressly prohibits a State from using “any information contained within [an] I-9 as the basis for a state law identity theft prosecution of an alien who uses another’s Social Security information in an I-9.” P appealed.