In 6-3 opinion that could have wider implications in criminal cases, the Supreme Court ruled expert witnesses can testify that most drug couriers caught at Mexican border know they’re transporting drugs
The U.S. Supreme Court issued a split opinion Thursday in a case originating out of San Diego, ruling that expert witnesses can continue to tell jurors that most drug couriers caught at the U.S.-Mexico border know they’re transporting drugs, even when the defendants argue they were unwitting “blind mules.”
The case, Delilah Guadalupe Diaz v. United States of America, centered around a specific rule of evidence in federal law dealing with a defendant’s mental state and knowledge of a crime, and the opinions of experts testifying about a defendant’s criminal intent.
The ruling has major implications for the San Diego region, where federal prosecutors charge hundreds of people each year with illegally importing drugs across the border, but could also have wider implications for defendants in other kinds of cases when there are questions of criminal intent.
In essence, the court ruled that an expert can testify about the criminal intent or mental state of most defendants charged with a particular crime, and that such testimony is not too general — the jury can still decide if a specific defendant is like most other defendants or not.
Justice Clarence Thomas authored the 6 to 3 majority opinion, which affirmed a previous ruling by the 9th U.S. Circuit Court of Appeals. The appeals court had ruled that Homeland Security Investigations Special Agent Andrew Flood had not violated the federal evidence rule — 704(b) — when he testified at Diaz’s trial that “in most circumstances, the driver knows they are hired … to take the drugs from point A to point B.”
Thomas wrote that Flood did not testify specifically that Diaz knew she was transporting drugs.
“Agent Flood asserted that Diaz was part of a group of persons that may or may not have a particular mental state,” the justice wrote. “Of all drug couriers — a group that includes Diaz — he opined that the majority knowingly transport drugs. The jury was then left to decide: Is Diaz like the majority of couriers? Or, is Diaz one of the less-numerous-but-still-existent couriers who unwittingly transport drugs? The ultimate issue of Diaz’s mental state was left to the jury’s judgment. As a result, Agent Flood’s testimony did not violate Rule 704(b).”
San Diego defense attorney Danielle Iredale, who first represented Diaz and raised the issue at trial, predicted in March after the Supreme Court heard oral arguments that the decision would involve “strange bedfellows” and be close. “I don’t think the split is necessarily going to be along the typical ideological lines,” Iredale predicted after attending the oral arguments in person.
She was right.
Justice Ketanji Brown Jackson, a President Joe Biden nominee, wrote a concurrence to Thomas’s opinion, joining the majority along with Republican-appointed justices John Roberts, Samuel Alito, Brett Kavanaugh and Amy Coney Barrett. Justice Neil Gorsuch, a nominee of President Donald Trump, wrote the dissent, joined by President Barack Obama-appointees justices Sonia Sotomayor and Elena Kagan.
Jackson wrote in her concurrence that the rule in question “is party agnostic,” a point that she had focused on during oral arguments.
“Indeed, the type of mental-state evidence that Rule 704(b) permits can prove essential not only for prosecutors, but for defendants as well,” Jackson wrote.
The government has acknowledged that Mexican drug-smuggling groups sometimes use the vehicles of unwitting victims — such as students or workers who cross the border at routine and predictable times — but maintains that such cases are rare. San Diego defense attorneys contend the use of blind mules is more common than the government will admit and beneficial to smugglers who can track the drug load with a hidden GPS, don’t have to pay the driver and need not worry about the driver snitching, stealing the drugs or acting nervous during inspections.
Federal authorities arrested Diaz, a U.S. citizen and Moreno Valley resident, in August 2020 at the San Ysidro Port of Entry after finding some 60 pounds of methamphetamine concealed within the doors of her vehicle. She maintained from the beginning that the car belonged to her boyfriend and she didn’t know about the drugs.
Before trial, Iredale unsuccessfully attempted to block the testimony of Flood, the federal agent, that drug-trafficking organizations typically don’t use blind mules because it’s too risky. The jury convicted Diaz, who then appealed to the 9th Circuit, again unsuccessfully.
The petition asking the Supreme Court to take up the case, filed by Stanford law professor Jeffrey L. Fisher, the co-director of Stanford’s Supreme Court Litigation Clinic, cited previous reporting from the Union-Tribune. It argued that the 9th Circuit’s interpretation of the evidence rule “lightens the Government’s burden to prove knowledge beyond a reasonable doubt” by allowing sweeping generalizations about a particular class of defendants rather than evidence specific to the actual defendant.
The rule at the heart of the case states in part that “an expert witness must not state an opinion” about a defendant’s state of mind. Congress amended the rule to its current form through the Insanity Defense Reform Act of 1984 in response to the acquittal of President Ronald Reagan’s would-be assassin, John Hinckley Jr. A jury found Hinckley not guilty by reason of insanity after hearing conflicting testimony about whether he met the legal standard for insanity.
In blind mule cases, the issue becomes not whether the driver is insane, but whether the driver knows he or she is committing a crime.
Gorsuch was scathing in his dissent, arguing that the “upshot” of the court’s majority opinion is that “the government comes away with a powerful new tool in its pocket.”
Wrote Gorsuch: “Prosecutors can now put an expert on the stand — someone who apparently has the convenient ability to read minds — and let him hold forth on what ‘most’ people like the defendant think when they commit a legally proscribed act. Then, the government need do no more than urge the jury to find that the defendant is like ‘most’ people and convict. What authority exists for allowing that kind of charade in federal criminal trials is anybody’s guess, but certainly it cannot be found in Rule 704.”
Gorsuch went on to argue that in Diaz’s case, prosecutors could have pointed to plenty of circumstantial evidence that would allow the jury to infer that she knew about the drugs and was not a blind mule.
“The government was free to argue to a jury, asking it to conclude that Ms. Diaz’s story was ‘transparently flimsy,’” Gorsuch wrote. “Day in and day out, the government secures convictions for the knowing importation of drugs in just this way … There was no need to gild the lily by calling to the stand an ‘expert’ in mindreading. And there is certainly no cause for this Court to sanction the practice.”
Gorsuch went on to write that “the problem of junk science in the courtroom is real and well documented … And perhaps no ‘science’ is more junky than mental telepathy.”
Jackson wrote in her concurrence with Thomas that she “fully (acknowledges) that there are serious and well-known risks of overreliance on expert testimony — risks that are especially acute in criminal trials.” But she wrote that there are other safeguards outside of Rule 704(b) to prevent misuse of expert testimony.
“This means, of course, that when faced with flawed or faulty testimony concerning the mental states of groups or categories of individuals, parties can utilize the traditional tools in a lawyer’s toolkit, like vigorous cross-examination and careful refutation in closing argument,” Jackson wrote.
Jackson wrote that district court judges also have a role to play by providing clear and specific instructions to jurors when they hear testimony about a defendant’s mental state or criminal intent.