Ignacio Flores-Figueroa (defendant) is a Mexican citizen who entered the United States illegally. In 2006, Flores-Figueroa gave his employer a fake Social Security card and alien-registration card. The employer alerted U.S. Immigration and Customs Enforcement (ICE) to Flores-Figueroa’s documentation. ICE determined that the numbers on his Social Security and alien-registration cards belonged to real people. Flores-Figueroa was charged with the crimes of entering the United States illegally and misusing immigration documents. Additionally, the Government (plaintiff) charged Flores-Figueroa with aggravated identity theft. A federal statute defines aggravated identity theft as a crime in which one “knowingly transfers, possesses, or uses, without lawful authority, a means of identification of another person.” The federal district court convicted Flores-Figueroa after a bench trial, and the appeals court affirmed the conviction. The United States Supreme Court granted certiorari.