DC Superior Court Judge Jason Park limited the scope of expert testimony in a homicide case, while deferring rulings on several pending motions on Oct. 31.
Charles Haythe, 34, is charged with second-degree murder while armed, carrying a dangerous weapon outside a home or business, and possession of a prohibited weapon for his alleged involvement in the Oct. 25, 2021 fatal stabbing of 26-year-old Aaron Langford on the 1600 block of 18th Street, SE.
Defense attorney Julie Swaney informed the court of their amended first expert witness notice, clarifying that their analyst would not testify about Haythe’s mental health condition. This comes as a response to the prosecution’s motion seeking to limit the expert’s testimony.
Judge Park questioned Swaney about the defense’s reference to a “cascade response”, a term used in their filings. Swaney explained that the phrase referred to the physiological “fight, flight, or freeze” reaction often seen in domestic violence situations, arguing that jurors should be educated on such patterns to understand Haythe’s behavior.
Judge Park expressed skepticism about the relevance of the expert testimony to the legal question of whether Haythe acted “reasonably.” While he did not see a clear connection, he allowed the defense to submit a supplemental written explanation defining the term and its significance. He cautioned that any testimony touching on the defendant’s state of mind could raise mens rea – intention or knowledge of committing a crime– issues and would need to be narrowly tailored.
Further discussion centered on the scope of the expert’s testimony, particularly her anticipated explanation of “domestic violence batterer typology.” Swaney said the expert intended to help jurors understand the victim and defendant’s romantic relationship. This would be accomplished through an explanation of common behavioral responses in abusive relationships, which would show how the defendant may have recognized the victim’s emotional “triggers”.
Judge Park again pressed the defense on the relevance of such testimony, noting that Haythe himself was not a clinician and could not be presumed to have professional insight into the victim’s psychology. He ultimately granted the prosecution’s motion to limit a doctor’s testimony.
The judge ruled that the expert may testify only about evidence and testimony presented in court, not about information obtained during her two prior interviews with the defendant. The prosecution requested access to those interviews, but the judge denied the request.
Whether the expert can effectively restrict her testimony to courtroom evidence will be reviewed at a future hearing before she takes the stand.
Judge Park also denied the prosecution’s motion to conduct an independent examination of the defendant, siding with the defense’s opposition.
The prosecution additionally asked Judge Park to rule on a defense motion to suppress evidence and a prosecution motion to admit evidence. The judge said he was not up to speed on either filings and would defer those decisions to a later date.
The parties are slated to reconvene on March 13, 2026.
