Expert Witness Profiler

Tag: Mens Rea

  • Psychology Expert Was Not Allowed to Opine on PTSD Symptoms

    Psychology Expert Was Not Allowed to Opine on PTSD Symptoms

    Defendant Bryant Wilson (hereinafter “Defendant”) was charged with voluntary manslaughter and possession of contraband in prison, following a prison fight at USP Canaan that resulted in the stabbing death of Defendant’s victim on November 28, 2021.

    Defendant did not contest that the fight happened, nor that the death of his victim resulted; rather, he asserted that he acted in self-defense.

    On November 10, 2025, Defendant notified the Government that he wished to offer the expert testimony of Dr. Stephen M. Timchack, PsyD at trial, pursuant to Rule 702 of the Federal Rules of Evidence. He indicated that Timchak would testify to Defendant’s symptoms consistent with Post Traumatic Stress Disorder (“PTSD”).

    Psychology Expert Witness

    Dr. Stephen M. Timchack, PsyD has extensive training and background in both clinical and forensic psychology.

    Timchack has held faculty positions at Wilkes University, Misericordia University, and the University of Scranton.

    Want to know more about the challenges Stephen Timchack has faced? Get the full details with our Challenge Study report.

    Discussion by the Court

    Psychiatric evidence cannot serve as a defense unless it renders the Defendant legally insane, and even if the Defendant is deemed insane, such evidence is inadmissible unless it negates the mens rea of the crime charged.

    Here, the Government thoroughly analyzed this issue with respect to the mens rea requirement of voluntary manslaughter.

    Defendant did not dispute the Government’s argument; instead, Defendant narrowly focused on admissibility of the psychiatric evidence for purposes of his self-defense claim. Thus, Defendant essentially conceded that his PTSD evidence did not truly negate mens rea.

    The PTSD evidence did not negate mens rea, so it was inadmissible. Furthermore, Defendant’s analogous reasoning did not hold up under scrutiny. As the Government noted,

    “Battered woman’s syndrome focuses on the perceived threat posed by the batterer on the battered, while PTSD, as shown by Timchak’s report, focuses on a more general, perceptual perceived threat posed to the PTSD-sufferer by his surroundings . . . Here, [Defendant] was not under duress or defending himself against his “batterer” or someone who had assaulted him in the past. So [Defendant’s] PTSD is much less probative to the disputed issues here than those in the cases relied on by the Defendant.”

    Even if the Court were to find that PTSD negates the mens rea of voluntary manslaughter in this case, the psychiatric evidence would still be inadmissible as both irrelevant and confusing to the jury.

    Held

    The Court granted the Government’s motion in limine to preclude the expert testimony of Dr. Stephen Timchak.

    Key Takeaway:

    Simply, PTSD does not constitute insanity, nor does PTSD negate the mens rea for voluntary manslaughter. The Court posits, as a theory, that PTSD could have inflamed Defendant’s reaction such that he carried out the killing in the heat of passion. In other words, PTSD likely offers an explanation, not a negation.

    Case Details:

    Case Caption: USA V. Wilson
    Docket Number: 3:24cr239
    Court Name: United States District Court, Pennsylvania Middle
    Order Date: November 17, 2025

    Please refer to the blog previously published about this case:

    Prison Expert Was Not Allowed to Opine on Proper Staff Procedure

  • Court Limits Psychiatry Expert’s Testimony, Citing Reliability Concerns 

    Court Limits Psychiatry Expert’s Testimony, Citing Reliability Concerns 

    Kevin Brent Buchanan had been charged with making threatening interstate communications. Specifically, the charges stemmed from five voicemails he allegedly left. The Government alleged that Buchanan recorded these voicemails from Utah. These voicemails, sent in late October 2023, targeted an organization that was headquartered in the District of Columbia.

    To defend himself, Buchanan designated Dr. Glen E. Johnson as an expert witness. Johnson is a board-certified psychiatrist. Evidently, he was expected to testify about Buchanan’s mental state. This testimony would relate to the time of the alleged offenses.

    Johnson was prepared to testify that Buchanan suffered from severe PTSD and recurring panic disorder. According to Johnson, Buchanan’s diagnoses means that Buchanan is prone to react reflexively and with poor impulse control. Johnson also stated that Buchanan “has never demonstrated any violence” or “following through with threats,” and he “poses no risk to anyone.” However, Buchanan has not submitted an expert report from Johnson, and neither his expert disclosure notice nor the accompanying attachments clearly set out the bases and reasons for Johnson’s opinions.

    Consequently, the Government filed a motion in limine requesting an order precluding Buchanan from offering evidence or argument at trial in support of a diminished capacity defense.

    Psychiatry Expert Witness 

    Dr. Glen E. Johnson graduated medical school 54 years ago and has spent the past 54 years in the field of psychiatry. Johnson has been an independently practicing psychiatrist for 47 years. Moreover, he became board-certified nearly 46 years ago. Johnson was a clinical instructor at the University of Utah Medical Center, Department of Psychiatry, for twelve years. Additionally, he was chairman of the Pioneer Valley Hospital Department of Psychiatry from 1986 through 1988, and has otherwise been affiliated with that hospital for 47 years.

    Want to know more about the challenges Glen Johnson has faced? Get the full details with our Challenge Study report.

    Discussion by the Court 

    Johnson’s proffered expert witness testimony about Buchanan’s reflexive and impulsive reactions could be relevant and helpful to the jury’s assessment of whether Buchanan had the requisite mens rea to commit the crimes with which he is charged in this case.

    i. Reliability 

    First of all, Johnson must not express an expert opinion to the jury about whether Buchanan was “unable to formulate the requisite specific intent to violate the statutes pursuant to which he is charged in the indictment.” 

    In other words, the Court held that a core part of the proffered expert opinion testimony described in Buchanan’s witness designation is plainly inadmissible.

    Second, Buchanan’s expert disclosure statement omitted necessary details about the scope of and basis for any other expert opinions that Johnson might be prepared to offer.

    Moreover, the Court observed that Buchanan’s opinion witness designation suggested that he may be planning to call Johnson both as a lay witness and as an expert witness, but Buchanan failed to delineate which topics Johnson will address as a lay witness and which he will address as an expert

    ii. Qualifications 

    The government argued that Johnson’s background lacked specific experience in forensic psychiatry, questioning the relevance of his testimony in assessing Buchanan’s mental state at the time of the alleged offenses.

    However, the Court noted that Johnson was qualified in general-practice psychiatry due to his decades of practice and board certification in that field.

    Therefore, the Court focused on whether Johnson’s experience and board certification in general-practice psychiatry were sufficient to provide expert testimony on Buchanan’s mental health, diagnoses, and related symptoms.
    According to the Court, if Johnson qualifies, his testimony will need to closely adhere to his expertise as a psychiatrist. In other words, he must testify based on expertise. However, the Court deferred final ruling on the reliability and admissibility of this testimony until after the forthcoming evidentiary hearing.

    Held 

    The Court granted in part, denied in part, and held in abeyance in part the government’s motion in limine .

    Specifically: 

    • The Court precluded Dr. Glen Johnson from opining on whether Buchanan did or did not have a mental state that constitutes an element of the crimes charged, including an opinion about whether he was capable of forming that mental state. 
    • Buchanan was ordered to produce a revised Rule 16(b)(1)(C) expert disclosure statement on or before April 25, 2025, containing “a complete statement” of all expert opinions that Buchanan intends to elicit from Johnson.
    • An pretrial evidentiary hearing was set to evaluate Johnson’s qualifications as an expert in general-practice psychiatry and the exact scope for any expert opinion testimony that Johnson intends to offer that would be admissible at trial.
    • Buchanan was allowed to introduce lay witness opinion testimony that is relevant to whether Buchanan was conscious of wrongdoing at the time of the alleged acts for which he is charged in this case.
    • The Court deferred final ruling on the admissibility under Federal Rule of Evidence 403 of the evidence at issue in the Government’s motion until the relevant issues arise at the forthcoming evidentiary hearing or at trial.

    Key Takeaway:

    Expert testimony regarding a Defendant’s mental state is strictly limited. Experts cannot offer opinions on whether the Defendant possessed the required mental state to commit the crime; their testimony must focus on diagnoses, the basis for those diagnoses, and the characteristics of relevant mental conditions.

    Case Details:

    Case Caption: United States V. Buchanan
    Docket Number: 1:24cr256
    Court Name: United States District Court for the District of Columbia
    Order Date: April 14, 2025