Evidence: Court limits testimony of expert in mass shootings

Although an expert in mass shootings can testify in a case where a man was charged with, among other crimes, transmitting in interstate and foreign commerce a threat to injure the person of another, he cannot provide expert testimony that implies a conclusion about a defendant’s mental state during the charged offense.

Background

Rui Jiang has been charged with: (1) attempted obstruction of free exercise of religious beliefs; (2) use of firearm during and in relation to a crime of violence and (3) transmitting in interstate and foreign commerce a threat to injure the person of another. The government has moved to exclude Jiang’s expert while Jiang has filed a motion in limine.

Analysis

Counsel for defendant provides a statement of the opinions that will be elicited from Dr. Fox, the bases and reasons for those opinions, Dr. Fox’s qualifications and other cases in which Dr. Fox has testified as an expert, thereby satisfying Rule 16’s requirements for expert disclosure. His testimony is relevant because a central issue at trial will be whether defendant intended to shoot individuals at Park Valley Church, and the defense states that Dr. Fox’s testimony will address how most individuals who contemplate engaging in a mass shooting behave.

Specifically, Dr. Fox’s testimony regarding how “most” individuals who carry out mass shootings behave will help the jury to understand the evidence presented and to determine a fact in issue—namely, whether defendant’s actions that day reflected the intention to carry out a mass shooting—while reserving that ultimate issue of mental state to the jury. Further, the proposed testimony appears reliable because it is not disputed that Dr. Fox’s background and extensive research demonstrates that he is an expert in the area of mass shootings.

However certain sections of Dr. Fox’s anticipated testimony – explicitly comparing defendant’s actions to those of most individuals contemplating engaging in a mass shooting – are impermissible because they imply a conclusion about defendant’s mental state during the charged offense. While Dr. Fox may testify generally about broad trends for individuals who engage in mass shootings, he cannot provide expert testimony that implies a conclusion about a defendant’s mental state during the charged offense. Permitting Dr. Fox to directly state that defendant’s behavior is consistent or inconsistent with the conduct of most individuals who commit mass shootings risks improperly suggesting intent.

Motion in limine

Defendant moves to preclude the government from referring to the standards for the Emergency Custody Order and Temporary Detention Order that were put in place after defendant was initially arrested at Park Valley Church. The government has indicated that it does not object to defendant’s motion in limine.

The court will therefore grant defendant’s motion in limine and preclude the government from referencing the standards for the Emergency Custody Order and Temporary Detention Order, unless defendant opens the door. The government will not be precluded, however, from eliciting testimony that defendant was taken into custody or that a basis for taking him into custody related to his mental health.

Government’s motion to exclude granted in part, denied in part. Defendant’s motion in limine granted.

United States v. Jiang, Case No. 1:24-cr-65, Feb. 27, 2025. EDVA at Alexandria (Alston). VLW 025-3-079. 12 pp.