The case involved drug dealer Marcus Andrew Burrage in Ames, Iowa, and the 1986 Anti-Drug Abuse Act.
One of Burrage's clients, longtime drug user Joshua Banka died in April 2010 following an extended binge that included buying heroin from Burrage, court records said.
The binge began on April 14 when Banka smoked marijuana, then stole oxycodone pills from a roommate. He crushed, cooked and injected the pills, then with his wife bought a gram of heroin from Burrage. His wife found him dead on the morning of April 15 and called 911.
Burrage pleaded not guilty to unlawfully distributing heroin, resulting in death. An expert at trial testified that Banka might have died even if he had not taken heroin. A federal judge instructed the jury the heroin only had to be a "contributing cause of death," and he was convicted. The judge gave him an enhanced sentence of 20 years.
A federal appeals court upheld the judge's instructions.
The U.S. Supreme Court, led by Justice Antonin Scalia, reversed. "At least where use of the drug distributed by the defendant is not an independently sufficient cause of the victim's death or serious bodily injury," Scalia said, "a defendant cannot be liable for penalty enhancement under [the federal act] unless such use is a but-for cause of the death or injury."
Two justices joined in a concurring opinion and the rest signed on to Scalia's prevailing opinion.