Jose Angel Carachuri-Rosendo (Carachuri) (plaintiff), a lawful permanent resident of the United States, was convicted of two misdemeanor drug possession offenses in Texas. The first conviction resulted after Carachuri pleaded guilty to possessing less than two ounces of marijuana. The following year, Carachuri pleaded no contest to possessing one tablet of Xanax without a prescription. The prosecutor elected not to seek an enhancement of the punishment based on Carachuri’s prior conviction. Thereafter, the Department of Homeland Security initiated removal proceedings against Carachuri under the Immigration and Nationality Act (INA). Although Carachuri conceded that he was subject to deportation, he argued that he was eligible for discretionary relief from removal under INA § 240A(a). The immigration judge held that Carachuri’s second simple possession conviction was an “aggravated felony” that made him ineligible for cancellation of removal. The Board of Immigration Appeals (BIA) affirmed the judge’s order. Carachuri filed a petition against Attorney General Eric Holder, Jr. (defendant) to appeal the BIA’s decision in federal district court. The appellate court affirmed the BIA’s decision on the ground that “[i]f the conduct proscribed by the state offense could have been prosecuted as a felony” under the Controlled Substances Act, the conviction qualifies as an aggravated felony. See Lopez v. Gonzales, 549 U.S. 47, 60 (2006). Carachuri appealed. The U.S. Supreme Court granted certiorari to review.