The Supreme Court has delivered a six-to-three verdict against a drug trafficking conviction, citing the admission of expert testimony that violated federal evidentiary rules. Delilah Diaz, a drug mule, was stopped at the United States-Mexico border in 2020 with over 54 pounds of methamphetamine, leading to a federal prosecution for importing the drugs.
Diaz’s legal team argued that testimony from Homeland Security Investigations special agent Flood breached federal rules by stating an opinion about her mental state or condition. Flood claimed that most couriers are aware they are transporting large quantities of drugs in similar cases, which the court initially allowed.
After a jury convicted Diaz, she appealed the decision, citing the testimony’s violation of federal evidentiary rules. The Court of Appeals upheld the conviction. However, the Supreme Court reversed the decision in a six-to-three opinion.
In the majority opinion, Justice Thomas was joined by Chief Justice Roberts and Justices Alito, Kavanaugh, Barrett, and Jackson, who filed a concurring opinion. Justice Gorsuch filed a dissenting opinion, joined by Justices Sotomayor and Kagan.
The case is now known as Diaz v. United States, No. 23-14 in the Supreme Court of the United States.
