Evidence; A law-enforcement officer’s testimony as an expert about the meaning of common words & phrases contained in text messages; FRE 702; Whether error was harmless; Double jeopardy; Sufficiency of the evidence to get a conviction at the first trial

The court held that the district court erred by allowing a law-enforcement officer to testify as an expert about the meaning of text messages between defendant-Glenn and the decedent where most of the messages “were not a proper subject for expert testimony, and [the officer] was not qualified to testify as an expert regarding those messages.” Glenn was convicted of two counts of distributing carfentanil and one count of using a telecommunications device to facilitate the transaction. One of the carfentanil counts was enhanced for causing death. He argued that the district court erred by permitting the officer (A) to testify as an expert as to the meaning of common words and phrases found in text messages between Glenn and the decedent (D). Applying the abuse of discretion standard to the parts of the text messages A interpreted and Glenn objected to, the court found that there were aspects of A’s “testimony, such as his interpretation of what ‘dope sickness’ means, or his statement that drug users ‘have also bartered things as material items and/or sex’ for drugs, that drew from his expertise. But, apart from those narrow instances, the text messages between Glenn and [D] were nearly devoid of any such specialized language, and [A] did not lay a foundation for how his expertise would be helpful in interpreting common words and phrases in texts. He did not discuss any qualifications for interpreting common words and phrases that would assist the jury in distinguishing between people exchanging drugs and people discussing something other than drugs, such as sex or money.” The court held that “the jury was just as competent as [A] to interpret the common words and phrases used in these text messages.” In addition, “[b]ecause so much of the case revolves around [A’s] testimony and the text messages in question,” the court lacked “a ‘fair assurance’ that the verdict was unaffected by [A’s] improper testimony.” As to whether a new trial was barred by double jeopardy, the court determined that, viewing “the evidence in the light most favorable to the prosecution, including [A’s] improper testimony,” the government offered “sufficient evidence to support each of the charges against Glenn.” The evidence that included A’s testimony was “sufficient to convict Glenn, but is not so overwhelming as to make the admission of the improper testimony harmless.” The court found no double jeopardy bar to retrying him. It vacated his convictions and remanded.