Coercive control is a legally recognized pattern of domestic abuse, and in California, it can form the foundation of a defense in a homicide case. Under California Evidence Code § 1107, expert testimony about intimate partner battering and its effects — including the psychological impact of prolonged coercive control — is admissible to explain why you believed you needed to act in self-defense against an abusive partner.
That legal reality matters because coercive control cases do not look like what most people picture when they think of domestic violence. There may be no broken bones, no police reports, no visible injuries at all. Instead, there is a pattern of isolation, surveillance, intimidation, and domination that can persist for years before something breaks. If you have lived under that pattern and now face a homicide charge, the case often turns on a single set of questions. Does the law recognize what you endured? Can a jury hear about it?
This page explains how California law defines coercive control, how it applies in a homicide defense, and how expert testimony brings the history of abuse into the courtroom.
What Does Coercive Control Mean Under California Law?
For most of California’s legal history, domestic violence law focused primarily on physical harm. That changed in 2021, when the Legislature added coercive control to California Family Code § 6320. The addition marked what the law recognizes as a significant shift toward acknowledging non-physical forms of domestic violence as legally recognized abuse.
This was not entirely new ground. In Rodriguez v. Menjivar, 243 Cal.App.4th 816 (2015), a California appellate court had already held that controlling and coercive behavior — including isolation, monitoring, and emotional abuse — constitutes “abuse” under the Domestic Violence Prevention Act. The court also found that the trial court erred by refusing to consider such conduct as a basis for issuing a protective order. What the 2021 amendment did was write that recognition into statute, making it explicit that coercive control is a form of domestic violence under California law.
This matters for criminal defense because the definition of “abuse” under Family Code § 6203 includes conduct that could be enjoined under § 6320. When coercive control entered § 6320, it entered the broader body of law through which California courts evaluate domestic violence — including the rules that govern how abuse history is presented in criminal cases.
Can Coercive Control Be the Basis of a Homicide Defense?
Yes, though not as a standalone defense. California Evidence Code § 1107 does not create a new legal defense called “coercive control” or “battered spouse syndrome.” Section 1107(d) is explicit: it is a rule of evidence, not a new substantive defense within the Penal Code. What it does is make expert testimony on intimate partner battering and its effects admissible to support existing defense doctrines — especially self-defense and imperfect self-defense.
Standard jury instructions integrate this evidence into homicide cases. CALCRIM No. 505 addresses justifiable homicide based on self-defense or defense of another. CALCRIM No. 571 addresses imperfect self-defense. In a case involving prolonged coercive control, the central question is what “reasonably believed” means for a person whose perception of danger has been shaped by years of abuse.
The California Supreme Court answered that question directly in People v. Humphrey, 13 Cal.4th 1073 (1996). The court held that expert testimony on battered women’s syndrome is relevant to both the subjective existence and the objective reasonableness of the defendant’s belief that self-defense was necessary. The statute now uses the broader term “intimate partner battering and its effects” under § 1107’s amended language. The trial court had instructed the jury to consider battering evidence only when evaluating whether the defendant actually believed she was in danger. The Supreme Court reversed, holding that the evidence must also be available to the jury when deciding whether that belief was objectively reasonable. A person who has been systematically terrorized perceives and responds to danger differently than someone who has not. The law requires the jury to account for that.
Where a jury finds the defendant genuinely believed they were in danger but that the belief was not objectively reasonable, the case does not automatically result in a murder conviction. CALCRIM No. 571 addresses imperfect self-defense as a lesser included theory, which can provide an alternative path that avoids a murder conviction. The difference in potential sentence between a murder conviction and a lesser charge can be enormous.
How Does a Jury Learn About the Abuse?
Through expert testimony governed by Evidence Code § 1107 and presented under CALCRIM No. 851, which is the standard jury instruction for intimate partner battering evidence offered by the defense.
Section 1107(a) permits a qualified expert to testify about “intimate partner battering and its effects, including the nature and effect of physical, emotional, or mental abuse on the beliefs, perceptions, or behavior of victims of domestic violence.” In practice, this means an expert can explain to a jury what coercive control looks like over time — the cycle of violence, why victims do not leave, and how prolonged abuse reshapes a person’s ability to assess threat. The Legislature broadened the statute’s terminology from “battered women’s syndrome” to “intimate partner battering and its effects” specifically to encompass all genders and relationship types.
The research on these effects is substantial. Studies of intimate partner violence victims have found that 75% of those in shelter populations met diagnostic criteria for PTSD and 54% for depression. Those rates reflect the severity of psychological harm even without ongoing physical violence. An expert can place those clinical findings before a jury so they understand the mental state of someone living under coercive control.
There is one critical boundary. In People v. Erickson, 57 Cal.App.4th 1391 (1997), the court held that an expert may testify about general behavioral patterns — how coercive control affects perception, and why a battered person would reasonably interpret certain conduct as life-threatening. But the expert may not testify that the defendant actually perceived danger or actually held the required mental state. That line exists because California Penal Code § 29 prohibits expert opinion on a defendant’s actual mental state. The expert provides the context; the jury applies it to the facts.
One additional protection matters here. Under § 1107(b), intimate partner battering testimony “shall not be considered a new scientific technique whose reliability is unproven.” The Legislature specifically exempted this evidence from Kelly-Frye/Daubert reliability challenges. The prosecution cannot argue that the science behind it is too new or uncertain to be admitted.
What If You Weren’t Being Physically Attacked at That Exact Moment?
This is the question at the center of most coercive control homicide cases, and it is the reason Humphrey matters as much as it does.
Traditional self-defense requires a reasonable belief in imminent danger. In many cases involving prolonged coercive control, the act that leads to a homicide charge does not occur during an active physical attack. It may happen during a lull in the violence, or in a moment where the abuser’s behavior signals to you — based on everything you have learned over months or years of abuse — that serious harm is coming. To someone unfamiliar with the dynamics of coercive control, the danger may not appear imminent. If you have been living inside it, the signs may be unmistakable.
Humphrey addressed this directly. By holding that battering evidence goes to the objective reasonableness of the defendant’s belief — not just whether the belief existed — the California Supreme Court ensured that juries must evaluate imminence through the lens of the defendant’s experience. The question is not whether a person with no history of abuse would have perceived the situation as immediately life-threatening. The question is whether a reasonable person who had endured the same pattern of coercive control would have perceived it that way.
This does not guarantee an acquittal. A jury may still find that the belief in imminent danger, however genuine, was not objectively reasonable even accounting for the abuse history. But that finding can lead to imperfect self-defense under CALCRIM No. 571, rather than a murder conviction. And when the defense effectively presents the full scope of the coercive control, juries have the evidence they need to find the belief was both genuine and reasonable. That is a complete defense under CALCRIM No. 505.
The stakes of how this evidence is presented are difficult to overstate. In California in 2024, 40.2% of female homicide victims were killed by a family member or intimate partner. These cases are not rare. The legal system increasingly recognizes that the people who end up charged in them may be the same people who spent years surviving abuse that the law now calls what it is.
Do I Need an Attorney Who Understands Coercive Control?
The legal tools described on this page — Evidence Code § 1107, CALCRIM Nos. 505, 571, and 851, and the Humphrey framework — exist in the law. But they do not activate themselves. Each one requires an attorney who understands both the criminal defense strategy and the dynamics of coercive control well enough to connect them.
That means working with qualified experts who can testify effectively under § 1107. It means framing jury instructions that ensure the abuse history reaches the reasonableness question. And it means preparing the case so that a jury can see what life looked like inside the relationship — not just what it looked like from outside on the day everything changed.
At Angelo Reyes Law in Carlsbad, California, every case is prepared as if it is going to a jury. That trial-first approach is designed to create leverage whether the matter resolves through negotiation or at trial, and it matters especially in cases where the full story — the one that includes years of abuse the system may not have seen before — needs to be told in a courtroom. Clients work directly with Angelo Reyes, not a paralegal or associate.
If you or someone you know is facing a homicide charge and coercive control is part of the history, contact Angelo Reyes Law to discuss the case.
