Conviction Reversed Because Police Officer Gave Unreliable Expert Testimony

Written on Wednesday, May 15th, 2019 by T.C. Kelly
Filed under: ExpertWitness

As is common in other states, the maximum sentence for a drug crime in South Carolina is tied to the quantity of drugs involved in the crime. For most drugs, quantity is measured by weight. Possessing ten pounds of marijuana is classified as a serious drug trafficking crime in South Carolina, while the penalties for possession of fewer than ten pounds are less severe.

While it might seem that the weight of a drug would be an uncontroversial fact, drug quantities are often subject to dispute. For example, marijuana weighs more at the moment it is harvested than it weighs after the plants and their buds lose water in the process of drying. Apart from questions about whether police officers have their thumbs on the scale when weighing marijuana, weight is something that can change over time.

Daniel Herrera was charged with possessing (and because of the quantity, “trafficking in”) 10 pounds, 2.78 ounces of marijuana. Had he been charged with possessing three fewer ounces, he would have been tried for a less serious crime.

South Carolina classifies drug trafficking as a violent crime, whether or not the crime involves violence. Defendants convicted of violent crimes in South Carolina must serve a larger percentage of their sentence than other offenders before they are eligible for parole.

Herrera denied that he knowingly possessed any marijuana at all. He also challenged the admissibility of the testimony about the weight of the marijuana that was given by the state’s expert witness, a police officer. The trial court allowed the testimony and Herrera was convicted. He renewed his challenge to the expert testimony on appeal.

The South Carolina Court of Appeals affirmed the conviction without giving serious attention to Herrera’s challenge to the expert testimony. The South Carolina Supreme Court accepted review of the court of appeals’ decision and reversed the conviction.

Expert Testimony

Herrera picked up a package at the post office containing six bags of suspected marijuana. The police arrested Herrera and charged him with drug trafficking. Herrera claimed he did not know that marijuana was in the package, a claim the jury rejected.

In most drug cases, prosecutors prove that the defendant possessed an illicit drug by calling a crime lab analyst who has a background in chemistry. The lab analyst will testify that one or more tests were conducted to confirm the identity of the suspected drug.

The Scientific Working Group for the Analysis of Seized Drug (SWGASD) recommends that the analysist conduct at least two tests, one of which should meet the “gold standard” for testing (such as infrared spectroscopy). When the best tests are not available, the SWGASD recommends conducting three independent tests, two of which should be in the “second best” category of drug identification tests.

According to the National Academy of Sciences, marijuana is usually identified by two of the “second best” tests — thin-layer chromatography and low-powered microscopic identification, as well as a presumptive color test. The presumptive color test is often used as a field test to support probable cause for an arrest, but the color test returns too many false positives to be reliable proof of drug identity.

While the SWGASD standards permit marijuana to be identified by its morphological characteristics, its standards require both microscopic or macroscopic examination of the suspected drug. When visual (including microscopic) examination is used to identify marijuana, SWGASD recommends that the identification be made by a botanist.

To prove that the package seized from Herrera contained marijuana and that the marijuana weighed more than ten pounds, the prosecutor relied on the testimony of Detective Jared Hunnicutt. Hunnicutt is not a botanist. The trial court decided that Hunnicutt was qualified to testify, despite having no scientific training, based on his training and experience.

Hunicutt’s training consisted of attending a single course in drug identification sponsored by a law enforcement group. His experience consisted of arresting people for suspected marijuana crimes.

Admissibility of Hunnicutt’s Expert Testimony

Remarkably, the supreme court decided that Hunnicutt’s qualifications as an “expert” presented a “close question.” The trial judge expressed discomfort in ruling that Hunnicutt had the qualifications of an expert, but ultimately acceded to the prosecutor’s questionable contention that police officers have more knowledge about the appearance of marijuana than jurors.

Like many other appellate courts, the supreme court decided the question of the officer’s qualifications in favor of the prosecution with scant attention to the foundation for Hunnicutt’s alleged expertise. Courts too often defer to a police officer’s claim that “I know marijuana when I see it” without considering SWGASD standards or National Academy of Sciences recommendations for drug identification testimony — standards that legitimate experts would understand and follow.

The court drew a line, however, when it considered Hunnicutt’s testimony about the weight of the marijuana. The prosecutor promised the trial judge that Hunnicutt would testify as an expert only as to drug identification, then broke that promise by asking Hunnicutt if he “tested” and “analyzed” the marijuana.

The judge sustained defense objections but apparently grew weary as the prosecutor continued to ask improper questions. The judge eventually allowed Hunnicutt to testify that he weighed the marijuana at the police department and that the marijuana weighed more than ten pounds.

Expert Standards for Weighing Drugs

Given the importance of weight to the charged crime, the supreme court concluded that the trial judge erred by allowing Hunnicutt to testify about the weight of the marijuana. Hunnicutt did not calibrate the scales he used to weigh the marijuana and had no personal knowledge of when or whether the department’s evidence technician had done so. A real expert would have used precise measuring instruments that had been recently calibrated to assure that the measurement of weight was accurate.

In addition, Hunnicutt weighed the drugs while they were inside the bags that held them. Packaging materials are not drugs and, with rare exceptions, the weight of packaging materials cannot be considered when measuring drug quantity.

Hunnicutt purported to account for the weight of the six baggies holding the drugs by weighing a different baggie that he found at the police department and multiplying that weight by six. It is fair to say that the supreme court was appalled by Hunnicutt’s “expert” methodology. The weight of a baggie that was “similar” in appearance to the bags that held the marijuana had no relevance to the actual weight of the marijuana minus the packages that held it.

Police officers are notoriously sloppy expert witnesses. Their unsound methodologies reflect their inherent bias in favor of the shared goals of police and prosecutors. Why the prosecution did not use a crime lab analyst or an independent expert to weigh the drugs is unclear, but its decision to rely on Hunnicutt to prove its case resulted in the reversal of Herrera’s conviction.

About T.C. Kelly

Prior to his retirement, T.C. Kelly handled litigation and appeals in state and federal courts across the Midwest. He focused his practice on criminal defense, personal injury, and employment law. He now writes about legal issues for a variety of publications.

About T.C. Kelly

Prior to his retirement, T.C. Kelly handled litigation and appeals in state and federal courts across the Midwest. He focused his practice on criminal defense, personal injury, and employment law. He now writes about legal issues for a variety of publications.