The U.S. Supreme Court ruled against Delilah Guadalupe Diaz, a California woman convicted of smuggling methamphetamine across the U.S.-Mexico border, upholding a lower court's decision to allow expert testimony that questioned her claim of being an unwitting 'blind mule'. In a 6-3 decision, the Court affirmed that expert witnesses can testify about the general knowledge of drug couriers, suggesting most couriers are aware they are transporting drugs. This ruling has significant implications for cases involving questions of criminal intent. Diaz was sentenced to seven years in prison for her 2021 conviction. The case centered on the interpretation of a federal evidence rule prohibiting experts from commenting on a defendant's mental state. Justice Clarence Thomas, writing for the majority, clarified that such testimony does not directly state the defendant's knowledge but allows the jury to infer it from general practices in drug trafficking.