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Self-proclaimed “blind mule” challenges expert testimony on drug-trafficking charge

A courier drops off a package at the Supreme Court

The Petitions of the Week column highlights a selection of cert petitions recently filed in the Supreme Court. A list of all petitions we’re watching is available here.

So-called “blind mules” are people who drive across the border without knowing their car has been packed with drugs. These people sometimes escape criminal charges because, to convict someone of trafficking drugs into the country, the government has to prove that they knew they were carrying controlled substances. This week, we highlight cert petitions that ask the court to consider, among other things, what role government expert witnesses can play in proving that a blind mule was not, in fact, blind to the drugs in their vehicle.

In August 2020, Delilah Diaz was driving from Mexico back to her home in California. At the border, an officer asked Diaz to roll down her window. The glass made a crunching noise as it slid into the doorframe. Agents searched the car and found nearly 28 kilograms of methamphetamine hidden inside the door panels.

The government charged Diaz with trafficking drugs into the country. Diaz insisted that she was a blind mule. The car, Diaz told the agents, belonged to her boyfriend living in Mexico, who let her drive it back to California after her daughter returned early in the car they originally drove down in together. She maintained that she had no idea about the hidden meth.

At trial, prosecutors called a Homeland Security agent as an expert witness. The agent testified that, in the majority of cases, couriers know when they are transporting large quantities of drugs across the border. Traffickers are rarely willing to risk hefty hauls of their product – and potential profit – on blind mules, the agent explained. The jury found Diaz guilty of drug trafficking, and a federal district court in California sentenced her to seven years in prison.

Diaz appealed her conviction, arguing that it was based on invalid evidence. The agent’s testimony that most large-scale drug couriers know they are carrying drugs violated the Federal Rules of Evidence, Diaz contended. Those rules prevent expert witnesses from “stat[ing] an opinion” about whether someone had a mental state or condition relevant to a criminal charge.

The U.S. Court of Appeals for the 9th Circuit affirmed Diaz’s conviction. Relying on a prior 9th Circuit decision, the court ruled that the DHS agent’s testimony complied with evidentiary rules. Under that decision, the court explained, expert witnesses are only barred from stating an express opinion about whether a particular person knew they were committing a crime, not from stating general opinions about similar defendants and the likelihood of their culpability.

In Diaz v. United States, Diaz asks the justices to grant review and reverse the 9th Circuit’s decision. She argues that nothing in the evidentiary rules makes an exception for statements of opinion like that of the DHS agent in her case, who, in her view, all but expressly said that he believed she was aware of the meth hidden in the car doors. Diaz contends that the testimony would have been thrown out in the U.S. Court of Appeals for the 5th Circuit, which has repeatedly excluded “testimony identical to the agent’s” in Diaz’s case. The 5th Circuit, she notes, includes Texas and, therefore, nearly all of the rest of the southern border.

A list of this week’s featured petitions is below:

E.I. du Pont de Nemours & Co. v. Abbott
Issue: Whether nonmutual offensive collateral estoppel can be applied to make the results of a handful of unrepresentative bellwether trials binding on the defendant in all pending and future cases in a multi-district litigation.

Diaz v. United States
Issue: Whether in a prosecution for drug trafficking — where an element of the offense is that the defendant knew she was carrying illegal drugs — Federal Rule of Evidence 704(b) permits a governmental expert witness to testify that most couriers know they are carrying drugs and that drug-trafficking organizations do not entrust large quantities of drugs to unknowing transporters.

Harrow v. Department of Defense
Issue: Whether the 60-day deadline in 5 U.S.C. § 7703(b)(1)(A) for a federal employee to petition the U.S. Court of Appeals for the Federal Circuit to review a final decision of the Merit Systems Protection Board is jurisdictional.

Recommended Citation: Kalvis Golde, Self-proclaimed “blind mule” challenges expert testimony on drug-trafficking charge, SCOTUSblog (Aug. 7, 2023, 6:13 PM),