The federal government (plaintiff) prosecuted Reginald Dinez Johnson and Carl Alexander (defendants) for narcotics crimes, in violation of 18 U.S.C. § 841, and conspiracy to commit such crimes, in violation of 18 U.S.C. § 846. The federal district court trial evidence established that, for seven or eight years, a group of conspirators illegally purchased and transported drugs from California to St. Louis, Missouri, where they sold the drugs to retail buyers. Although neither Johnson nor Alexander was an original member of the conspiracy, several conspirators testified that, later, Johnson often rode with them in a chase vehicle to escort a courier truck carrying drug-purchase money or drugs across the country. Jason Miller testified that Brown once helped unload a courier truck. Two witnesses testified that, at least twice, Alexander joined the conspirators in flying to California or Texas to make drug buys. Brown and Alexander testified that they were merely present on these occasions, and neither knew of, nor participated in, the conspiracy. The jury convicted all four defendants. On appeal to the Eighth Circuit Court of Appeals, Brown and Alexander argued that the evidence was insufficient to support their convictions for conspiracy.