Amicus brief filed for the reversal of the decision by the Court of Appeals from the Eighth Circuit in the case of the Immigration and Customs Enforcement (ICE)’s workplace raid at the Agriprocessors meatpacking plant in Postville, Iowa. ICE demonstrated the practical effects of failing to require knowledge of the defining element of 18 US.C. § 1028A—whether the identification at issue is “of another person.” In Postville, the crime of aggravated identity theft, which carries a two-year mandatory sentence enhancement, was stretched to reach immigrant workers with low levels of culpability. The Eighth Circuit’s reading produced arbitrary results. These arbitrary results were not necessary, as Congress’s false document scheme provides for independent and flexible punishment when immigrants knowingly use false documents. By extending the charge of aggravated identity theft beyond its intended bounds, the Eighth Circuit’s reading of 18 U.S.C. § 1028A contravened the bedrock criminal law principle that punishment should be calibrated to culpability. This brief argues that the Court should therefore limit its interpretation of the knowledge requirement in 18 U.S.C. § 1028A to reinforce the link between culpability and punishment and avoid undermining Congress’s immigration law.