## Facts

- Beverly Ibn-Tamas was charged with second-degree murder while armed for fatally shooting her husband, Dr. Yusef Ibn-Tamas, in their home where he also maintained a medical office.
- She testified that during their three-and-a-half-year marriage her husband repeatedly physically abused her, with cycles of violence followed by calmer periods.
- On the morning of the killing, she testified that an argument escalated into violence: her husband repeatedly hit her while she was pregnant, dragged her upstairs, kicked her in the abdomen, and threatened her with a gun while ordering her to leave.
- After a lull, she testified she saw him again in the office doorway, believed he was armed, and feared imminent death or serious bodily harm; she then picked up his gun and fired.
- The husband’s secretary testified she heard the husband plead not to be shot again and heard the defendant say words indicating she would never leave him.
- The defense theory was self-defense, asserting that prior battering informed the reasonableness of her perception of imminent danger.
- The prosecution theory was that she ambushed her husband, motivated by fear of eviction and resentment over abuse and affairs, and argued her conduct (staying, not contacting police) was inconsistent with genuine fear.
- At the second trial, the court excluded proposed expert testimony on battering and its effects offered to explain the defendant’s behavior and perception of danger; the jury convicted.

## Issues

1. Whether the trial court erred by excluding expert testimony on battering and its effects offered to support the defendant’s self-defense theory.
2. Whether the prosecution could use the defendant’s prior testimony from the first trial to impeach her at the second trial.
3. Whether prosecutorial comment about the defendant consulting counsel before police interrogation warranted reversal.
4. Whether questioning about the defendant’s beneficial interest in her husband’s life insurance was improperly admitted.
5. Whether an asserted variance between the prosecution’s opening statement and the evidence required reversal.
6. Whether the trial court erred by refusing a requested instruction tailoring self-defense to the defendant’s pregnancy and physical condition.

## Decision

- The court affirmed the conviction as to five claims of error (impeachment with prior testimony, prosecutor’s comments, life-insurance questioning, variance, and the requested instruction).
- On the exclusion of expert testimony about battering and its effects, the court held the trial court’s analysis was inadequate for appellate review.
- The court remanded for further proceedings and additional findings and conclusions on whether the proffered expert testimony should be admitted under proper evidentiary standards.
- The court rejected exclusion based solely on the view that the testimony would “invade the province of the jury,” but did not order admission; it required a reliability and relevance assessment.

## Legal Principles

- Expert testimony is not inadmissible merely because it bears on credibility or may influence the factfinder; the question is whether specialized knowledge will assist the trier of fact.
- A trial court must assess whether proposed scientific or specialized expert testimony is sufficiently reliable, including whether the methodology has achieved general acceptance in the relevant professional community (a Frye-type inquiry in the jurisdiction).
- Expert testimony concerning battering and its effects may be relevant to a self-defense claim to help jurors evaluate the reasonableness of the defendant’s perception of imminent danger and to explain behavior that lay jurors may view as illogical (e.g., remaining with an abuser, not seeking police help).
- Such testimony must be properly limited: it may describe patterns and effects and relate them to case circumstances, but should not directly opine on guilt or the defendant’s truthfulness.
- Appellate review requires an adequate record showing the trial court’s reasoning on relevance, reliability, and any probative-prejudice balancing.

## Conclusion

The court left the conviction intact on most issues but required the trial court to reconsider, with explicit findings, whether expert testimony on battering and its effects should have been admitted to support the defendant’s self-defense claim, applying reliability and relevance standards rather than excluding it simply for purportedly usurping the jury’s role.


Ibn-Tamas v. United States, 407 A.2d 626 (D.C. 1979)