---
title: "Psychiatry Expert Witness’ Testimony Regarding the Criteria for Cannabis Use Disorder Admitted"
meta:
  "og:description": "Psychiatry expert witness' testimony deemed relevant to determine whether Defendant knowingly possessed firearms while being an unlawful user of a controlled substance"
  "og:title": "Psychiatry Expert Witness’ Testimony Regarding the Criteria for Cannabis Use Disorder Admitted"
  author: "Expert Witness Profiler"
  description: "Psychiatry expert witness' testimony deemed relevant to determine whether Defendant knowingly possessed firearms while being an unlawful user of a controlled substance"
---

# Psychiatry Expert Witness’ Testimony Regarding the Criteria for Cannabis Use Disorder Admitted

Posted on August 7, 2024 by Expert Witness Profiler

Defendant Ryan Vangdy is charged with knowingly possessing firearms while being an unlawful user of a controlled substance.

The government filed a motion to exclude Defendant’s expert, [Dr. Gregory Nawalanic](https://expertwitnessprofiler.com/expert-witness/Gregory-Nawalanic/1559999). The government argued that the Court can exclude Nawalanic under [Rule 702](https://www.law.cornell.edu/rules/fre/rule_702#:~:text=Rule%20702%20sets%20forth%20the,is%20a%20relatively%20narrow%20inquiry.) for several reasons, specifically that the testimony is irrelevant, unhelpful to the jury, only serves to confuse the issues, and is likely to introduce inadmissible hearsay.

## **Psychiatry Expert Witness**

[Gregory Nawalanic, Psy.D.](https://expertwitnessprofiler.com/expert-witness/Gregory-Nawalanic/1559999), is a clinical assistant professor in the Department of Psychiatry and Behavioral Sciences at the University of Kansas Medical Center and the clinical director of Psychology Services at The University of Kansas Health System’s Strawberry Hill Campus.

In addition to supervising the behavioral health staff, he provides clinical instruction to psychology interns and postdoctoral fellows, as well as psychiatry residents. He also operates as part of the executive leadership of the facility.

Along with a bachelor’s degree and a master’s degree in psychology from Florida International University and Pepperdine University, respectively, he also holds a master’s degree and a doctor of psychology in clinical psychology from the American School of Professional Psychology at Argosy University.

[Get the full story on challenges to Gregory E. Nawalanic’s expert opinions and testimony with an in-depth Challenge Study.](https://app.expertwitnessprofiler.com/login?eId=1559999)

## **Discussion by the Court**

To begin with, the Defendant proposed to introduce testimony from Gregory Nawalanic regarding the DSM-V criteria for cannabis use disorder, and to testify as to the difference between “frequent and infrequent” use of controlled substances.

Defendant’s expert disclosure indicated that Nawalanic would testify that a hypothetical user who consumed marijuana two to four times a month would not meet the criteria for being diagnosed with cannabis use disorder under the DSM-5. Nawalanic would not offer an opinion as to whether Defendant was an unlawful user of a controlled substance on October 6, 2021.

The Court found that Nawalanic’s testimony was relevant to the issues being presented to the jury. The primary inquiry for the jury is whether Defendant possessed a firearm in or affecting interstate commerce when he was a regular and ongoing user of a controlled substance.

Cannabis use disorder would make it more likely that the individual was an unlawful user within the meaning of the statute. Moreover, the Court held that this potentially helpful information was not greatly outweighed by the risk of confusion because Nawalanic is not trying to testify to the ultimate legal issues, and any hearsay concerns can be dealt with by contemporaneous objection.

## **Held**

The Court denied the Government’s motion to exclude Dr. Gregory Nawalanic’s testimony.

## **Key Takeaway:**

In conclusion, Nawalanic’s testimony provided the Court with potentially helpful information to determine whether Defendant possessed a firearm in or affecting interstate commerce when he was a regular and ongoing user of a controlled substance.

## **Case Details:**

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