Marcus Burrage (defendant) sold one gram of heroin to Joshua Banka. Banka had already smoked marijuana; stolen oxycodone pills; and crushed, cooked, and injected the oxycodone when he purchased the heroin. After buying the heroin, Banka cooked and injected it several times that night into the next morning. Banka then died of a drug overdose. Burrage was charged with violating the provision of the federal Controlled Substances Act that applies if a death or serious bodily injury results from the use of such substance that was unlawfully distributed. At trial, two medical experts testified. Banka had heroin, codeine, alprazolam, clonazepam, and oxycodone in his system at the time of his death. Both experts testified that the heroin was a contributing factor to Banka’s death, but neither expert could state whether Banka would have lived if he had not taken the heroin. The jury convicted Burrage, and he was sentenced to the mandatory minimum sentence of 20 years. Burrage appealed.