Samuel Johnson (defendant) was a felon with an extensive criminal record. Johnson was being monitored by federal authorities, who suspected Johnson was planning to commit acts of terrorism. Johnson eventually showed an undercover agent several firearms in his possession. Johnson was then arrested and pleaded guilty to being a felon in possession of a firearm, in violation of federal law. The government (plaintiff) requested an enhanced sentencing under the Armed Career Criminal Act (the act). The act held that a felon in possession of a firearm faced more severe punishment if the felon had three or more previous convictions for violent felonies. A violent felony was defined as any felony involving conduct that presented a serious potential risk of physical injury to another. This section of the act was known as the residual clause. The government argued that three of Johnson’s previous convictions, including unlawful possession of a short-barrel shotgun, qualified as violent felonies. The trial court sided with the government, and sentenced Johnson to a 15-year prison term under the act. Johnson appealed his conviction. The Supreme Court granted certiorari on the issue of whether the residual clause was compatible with the Constitution’s prohibition on vague criminal laws.