Toxicology expert witness advises on faulty prison drug test claim


toxicology expert witness marijuanaA forensic toxicology expert witness for the defense opines on a case involving a prison inmate who tested positive for marijuana use, claiming that the results of a drug test were faulty. The plaintiff is an inmate at a federal prison. He sued the defendant laboratory and two of its employees alleging that anti-retroviral medication he was taking caused his random-testing urine specimen to test positive for cannabinoids in a gas chromatography and mass spectrometry (GC/MS) chemical analysis performed at the lab. Plaintiff asserts that he has never used marijuana in prison and that his medication caused the false-positive result.

According to plaintiff, defendants “failed to adhere to strict and exacting requirements for testing before certifying a specimen as positive for illicit drug use” and incorrectly informed the prison that his medication had no effect on the positive result. He asserts that defendants were liable for several torts, including negligence, intentional infliction of emotional distress, breach of contract, breach of fiduciary duty, defamation, libel, slander and personal injury. An expert in forensic science was sought to opine on the issue.

Question(s) For Expert Witness

  • 1. What was the standard of care for the lab?
  • 2. Was it met?

Expert Witness Response

Expert-ID:

The sample was received by the lab. The bag containing the urine specimen was inspected for evidence of tampering, and none was found. After inspection of the external seals, the bag was opened by a lab employee and the specimen bottle was checked for integrity of the bottle seal, which was present. The bottle was then compared against the chain of custody documentation to ensure the information matched and it did.

A lab scientist performed a GC/MS analysis on the sample and found it was positive for THCA in the amount of 11.9 ng/ml, which is nearly three times the limit set by the Bureau of Prisons contract as being considered “positive” for ll-nor-9-carboxy-delta9-THC. A toxicologist at the lab notified the prison that plaintiff’s medication would not produce a false positive.

It is my professional opinion that the plaintiff’s urine sample was correctly certified and reported as being positive for the presence of THCA following the GC/MS analysis. It is also my professional opinion that defendants all met the standard of care applicable to toxicologists when analyzing and certifying results of GC/MS tests. It cannot be stated to a reasonable degree of medical or scientific certainty that the plaintiff’s urine sample analyzed by defendants was contaminated in any fashion or that other urine samples analyzed prior to plaintiff’s sample had any appreciable “carryover” effect that would potentially result in a “false positive” being found for plaintiff’s urine sample in question. Further, the reported medication(s) taken by plaintiff cannot cause a “false positive” under GC/MS analysis.

The GC/MS machine utilized by defendants in this case was correctly calibrated prior to its usage to analyze the plaintiff’s sample. Adequate controls were utilized, and the accuracy of the measurements of the GC/MS machine utilized by defendants should be considered reliable. The methodology used by the defendants met the applicable standard of care. The sample was analyzed following both positive and negative control samples, which confirmed the reliability of the results from the GC/MS process.

The expert is a forensic toxicologist who practices analytical and forensic toxicology.

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