## Facts

- Angelique Lyn Lavallee lived in a long-term, volatile common-law relationship marked by serious and repeated physical abuse by Kevin Rust.
- On the night of the killing, Rust assaulted Lavallee, threatened that either she would kill him or he would “get her,” and she feared for her life.
- Rust handed Lavallee a gun; she first fired through a window screen and contemplated shooting herself.
- As Rust turned to leave the room, Lavallee shot him in the back of the head.
- Lavallee did not testify; she relied on self-defense under Criminal Code s. 34(2), supported primarily by expert psychiatric evidence.
- A psychiatrist experienced with battered women testified about the pattern of abuse, Lavallee’s terror and perceived inability to escape, and opined that she sincerely believed she would be killed that night.

## Issues

1. Whether expert evidence on battered woman syndrome was admissible and necessary to assist the jury in evaluating the reasonableness elements of self-defense.
2. Whether the psychiatrist’s opinion was inadmissible, or required stricter limiting instructions, because it relied in part on hearsay or other inadmissible material.
3. How the requirements of self-defense under s. 34(2)—including “reasonableness” and any “imminence” concept—apply when an abused woman kills her abusive partner.

## Decision

- The Supreme Court of Canada allowed Lavallee’s appeal and restored the jury acquittal.
- Expert evidence on battered woman syndrome was admissible and properly received to assist the jury on the reasonableness of Lavallee’s perceptions and response.
- The trial judge’s instructions adequately addressed the proper use and weight of the expert evidence and its factual foundations.
- Self-defense under s. 34(2) does not require that an abused woman wait until an assault is underway before her apprehension of death or grievous harm can be found reasonable.

## Legal Principles

- Expert opinion evidence is admissible where it is relevant and necessary to help the jury evaluate matters outside ordinary experience, including the effects of prolonged domestic abuse on perception and decision-making.
- Evidence concerning battering and its psychological effects does not create a separate defense; it may inform the jury’s application of the objective “reasonableness” requirements of self-defense to the accused’s circumstances.
- The reasonableness inquiry in self-defense may take account of the accused’s situation, including an abused woman’s experience, to avoid reliance on common misconceptions about leaving abusive relationships and assessing danger.
- “Imminence” is not a rigid prerequisite; the accused need not wait for a physical assault to be in progress if, in context, apprehension of death or grievous harm is reasonable.
- An expert may rely on some otherwise inadmissible information in forming an opinion, so long as there is sufficient admissible evidence to support the essential factual basis and the jury is properly instructed on the limited use of the underlying material.

## Conclusion

The Court restored Lavallee’s acquittal, holding that expert testimony on battered woman syndrome was properly admitted to assist the jury in applying self-defense and that the reasonableness of apprehended danger and responsive force must be assessed in light of the accused’s history of battering without a strict requirement that an attack be underway.


R. v. Lavallee, [1990] 1 S.C.R. 852 (Can.)