Supreme Court upholds California man's drug trafficking conviction based on expert opinion

The Supreme Court on Thursday upheld a California woman's drug trafficking conviction, based in part on expert testimony that criminal gangs rarely use “indiscriminate mules” to transport drugs across the southern border.

In a 6-3 decision, the justices rejected Delilah Diaz's claim that the expert testimony was unfair and illegal because it strongly suggested to jurors that she must have known that drugs were hidden in his car.

Federal rules of evidence say an expert cannot express an opinion about the “mental state or condition” of a defendant, but judges said the expert's testimony about trafficking operations of drugs in general did not violate this rule.

Liberal Justice Ketanji Brown Jackson joined most of the court's conservatives in the Diaz v. UNITED STATES. A former trial judge, she said experts often testify on both sides of the case.

“This case illustrates the importance of mental state evidence to both parties in a criminal trial,” Jackson wrote in a concurring opinion. “The government expert estimated (based on his nearly 30 years of experience as a special agent) that “in most cases” drug couriers know they are transporting drugs. …It should be noted, however, that the government was not the only party that relied on this type of mental state evidence at trial; Diaz called an automotive expert who testified that a driver of his car would almost certainly not know that it contained drugs.

In August 2020, Diaz, a U.S. citizen, was arrested at a border crossing while returning from Mexico. When a Border Patrol agent asked her to roll down one of the car windows, she said it was manual. When he tried, he heard a “sound like a creak in the door.”

When the car was stopped and checked, officers discovered 56 packages of methamphetamine hidden inside the door panels and under the trunk mat. The meth weighed just over 54 pounds and had an estimated retail value of $368,550.

Diaz said the car belonged to her boyfriend and that she knew nothing about the drugs.

She was charged with drug trafficking, and prosecutors had to prove to the jury that she knew she was transporting drugs.

They called Andrew Flood, a Department of Homeland Security special agent, who said that, in his experience, drug dealers “generally don't give large quantities of drugs to people who don't know they're getting them.” transport”.

Diaz was convicted and sentenced to seven years in prison. A federal judge in San Diego and the 9th Circuit Court of Appeals rejected his claim that the agent's testimony violated federal rules.

The Supreme Court agreed to hear his appeal, but upheld his conviction on Thursday.

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“Because Officer Flood did not express an opinion on whether Diaz herself knowingly transported methamphetamine, her testimony did not violate” federal rules, Judge Clarence Thomas said in the name of the majority. “An expert's conclusion that 'most members' of a group have a particular mental state does not constitute an opinion about the defendant.”

Chief Justice John G. Roberts Jr. and Justices Samuel A. Alito Jr., Brett M. Kavanaugh, Amy Coney Barrett and Jackson agreed.

Disagreeing, conservative Justice Neil M. Gorsuch said “the government walks away with a powerful new tool in its pocket.” Prosecutors can now put an expert on the stand — someone who apparently has the practical ability to read minds — and let him speak. about what “most” people like the accused think when they commit a legally prohibited act. . . . What authority exists to authorize this kind of charade in federal criminal trials is anyone's guess, but it certainly cannot be found in the federal rules of justice. evidence.

Justices Sonia Sotomayor and Elena Kagan agreed with Gorsuch.

San Francisco attorney Hillary Irvin, a former federal prosecutor, said the ruling “marks a dark day for criminal defendants.”

which “rely on the court and the gatekeeping function of the law to exclude evidence that would virtually guarantee a verdict in favor of the government.”

But “in reality, juries rely on expert testimony to make critical decisions about the defendant's conduct,” Irvin continued. “Now the government can present a witness to guide juries directly to the government's verdict.”

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This story was originally published in the Los Angeles Times.