Supreme Court Weighs Convicted Border Drug ‘Mule’ Appeal

(Manuel Balce Ceneta/AP)

The Supreme Court on Tuesday is set to consider a California woman’s bid to overturn her conviction for smuggling drugs across the U.S.-Mexican border in a legal dispute over her defense she acted unwittingly as a “blind” drug mule.

The justices will hear arguments in Delilah Guadalupe Diaz’s appeal after a lower court refused to exclude testimony by an expert witness who cast doubt on her claim that she did not know that methamphetamine valued at $368,550 was hidden in the door panels of the car she was driving.

The case tests how far law enforcement agents testifying as expert witnesses can go in telling a jury that defendants in certain drug trafficking cases generally have a “guilty mind.”

A jury in federal court in San Diego found Diaz guilty in 2021 of illegally importing the methamphetamine, a crime that required knowledge that she knew the drugs were in the car. Diaz was sentenced to seven years in prison.

People who smuggle drugs across borders, sometimes called “mules,” may do so for profit but also sometimes do it unwittingly, transporting illegal substances that were planted on them. These individuals are often called “blind” mules.

The justices will examine whether allowing such expert testimony violates the longstanding Federal Rules of Evidence governing the types of evidence allowable in legal cases.

Diaz’s lawyers have argued the testimony in her case broke a rule barring expert witnesses from offering opinions on the “mental state” of defendants related to an alleged offense and whether they knew they were committing a crime.

Her lawyers said that allowing generalizations during a trial that suggest a defendant must be guilty is “grossly unfair,” undermining the jury’s duty to assess the defendant’s guilt.

U.S. District Judge Anthony Battaglia allowed the prosecution’s expert witness, a Homeland Security special agent, to testify that “in most circumstances, the driver knows they are hired.” The expert also told the jury that drug-trafficking organizations generally do not entrust large quantities of drugs to unknowing couriers.

In 2020, border inspectors ordered Diaz, a resident of Moreno Valley, California, to roll down a window of the Ford Focus vehicle she was driving and heard a “crunch-like” sound, later finding 56 packages containing more than 24 kilograms of pure methamphetamine. Diaz denied knowledge of the drugs.

She carried two cellphones – one locked that she could not open – and claimed that the car belonged to a boyfriend she had visited in Mexico whose phone number and residence she could not identify. The car also had a hidden GPS device.

The San Francisco-based 9th U.S. Circuit Court of Appeals rejected her appeal last year.

The Supreme Court’s ruling is expected by the end of June.