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Sunday, December 10, 2023 | Back issues
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Expert testimony in drug cases will undergo Supreme Court review

A California woman says she did not know the car she was driving contained over $300,000 worth of drugs and thinks the government shouldn’t be able to speculate if she did.

WASHINGTON (CN) — The Supreme Court took up a dispute over expert witness testimony in drug trafficking on Monday. 

In a case brought by Delilah Guadalupe Diaz, the high court will decide how the government proves couriers know they are trafficking drugs. 

“An essential element of proving importation of illegal drugs in violation of the Controlled Substances Act is that the defendant knew she was transporting drugs,” Jeffrey Fisher, an attorney with the Stanford Law School Supreme Court litigation clinic representing Diaz, wrote. “This element is ‘necessary to separate wrongful conduct from ‘otherwise innocent conduct.''" 

Per their custom, the justices did not provide any comments on the grant. 

Diaz was driving back to California after a trip to Mexico in 2020 when she was stopped by a border agent. The agent became suspicious of Diaz after hearing a crunching sound when she rolled down her window. On further inspection, 61.56 pounds of methamphetamine — valued by the government at $368,500 — was found hidden in the door panel of her car. 

Diaz claims she had no idea the drugs were in the vehicle, which belonged to her boyfriend. She said her boyfriend let her drive his car, saying he would pick it up in a few days. 

The government charged Diaz with violating the Controlled Substances Act, which requires the courier to know they were transporting drugs. Diaz has maintained she did not know the car she was driving contained drugs. 

Diaz asked the trial court to prevent expert witnesses from testifying that she likely knew there were drugs in the car. Experts say typical drug couriers know what they are doing, since traffickers do not entrust large and valuable quantities of narcotics to unknowing couriers. Diaz claimed this testimony would violate federal evidence rules by commenting on Diaz’s knowledge. 

The court denied Diaz’s attempt to exclude expert testimony on her knowledge of the drugs she was carrying and a jury found Diaz guilty. She was sentenced to seven years in prison. The Ninth Circuit rejected Diaz’s arguments on appeal. 

Diaz urged the justices to review her case, arguing the lower courts had split on the question. The Fifth Circuit has prohibited explicit opinions on mental state. 

“The circuit split is clear and entrenched, and it extends even beyond the Ninth and Fifth Circuits,” Fisher wrote. “The issue is significant. And the Ninth Circuit’s position is wrong.”

The government disagreed that circuit disagreement on this issue was so broad and urged the justices not to review it in this matter. 

“The scope of circuit disagreement is narrow, and any error in this particular case was harmless,” U.S. Solicitor General Elizabeth Prelogar wrote. “This Court has previously denied a petition that presented a similar issue, and it should follow the same course here.” 

The government declined to comment on the high court’s grant. Attorneys for Diaz did not respond to requests for comment. 

Follow @KelseyReichmann
Categories / Appeals, Criminal

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