Published September 26, 2026
The Evidentiary Challenge
Coercive control, a pattern of behavior involving isolation, surveillance, manipulation, and domination within intimate relationships, presents a distinctive evidentiary problem. Domestic abuse operates as a pattern of domination, intimidation, and deliberate impediment of an intimate partner’s rights, and laws addressing coercive control are designed to address damage inflicted apart from physical violence. Unlike a discrete assault that produces visible injury, coercive control unfolds over time through cumulative acts that may appear innocuous when viewed in isolation. A pattern of controlling or coercive behaviour can be well established before a single incident is reported, and in many cases the conduct might seem innocent, especially if considered in isolation of other incidents. This gap between what coercive control looks like in lived experience and what courts can interpret from individual pieces of evidence has made expert witness testimony on coercive control a central, and contested, feature of domestic abuse litigation.
How Expert Testimony Functions in Domestic Abuse Proceedings
Expert testimony in domestic abuse cases generally takes two forms. In the “general expertise” model, an expert witness may know little about the specific case and testifies about domestic abuse dynamics in general terms, while lawyers can ask hypothetical questions that demonstrate how the information might pertain to the facts at hand.
In the “case-specific” model, expert witnesses write reports and testify to facts specific to the case. Case-specific experts review materials that may include police or medical reports, psychological evaluations, guardian ad litem reports, court documents, relevant communication records and photographs, and may conduct a domestic violence or coercive control interview and assessment with the alleged victim.
The role of expert testimony in domestic abuse proceedings has expanded significantly. Legal scholarship has traced the development of expert testimony in domestic violence cases from its initial exclusive use as a defense tool to support self-defense claims to its present use by prosecutors to explain a complainant’s recantation or other behavior that may puzzle jurors. Expert witnesses are likely to teach the court about research on coercive control, definitions of the issue and explanations as to why it occurs, and why a victim might recant, lie, comply with, defend, or stay with the abuser.
Admissibility Standards and the Expert Witness
In the United States, the admissibility of expert witness testimony on coercive control is governed by evidentiary frameworks that vary by jurisdiction. Under the federal standard clarified in Daubert v. Merrell Dow Pharmaceuticals, Inc. (1993), expert testimony may be offered where a witness’s “scientific, technical, or other specialized knowledge will help the trier of fact,” provided it is based on sufficient facts or data and is the product of reliable principles and methods. Daubert established four factors for evaluating expert testimony: whether a theory can be tested, whether it has been subjected to peer review, its known or potential rate of error, and the degree of widespread acceptance in the relevant field.
Some domestic violence experts rely on the framework of Battered Women’s Syndrome, while others have moved toward the coercive control framework as a model they consider more favorable to victim-survivors. This shift carries implications for coercive control court evidence, because the coercive control model asks the court to assess a pattern of conduct over time rather than a psychological syndrome within the victim. Courts applying the Daubert standard or its state equivalents must determine whether expert testimony grounded in coercive control theory meets the threshold of methodological reliability.
The Challen Case and the Influence of Expert Evidence
The case of Sally Challen in England and Wales illustrates how expert testimony on domestic abuse can reshape legal outcomes. In February 2019, the Court of Appeal overturned Challen’s murder conviction, and it was the first time that expert evidence about the impact of coercive control appears to have played a part in the Court of Appeal quashing a conviction. Fresh evidence on coercive control and fresh psychiatric evidence supported the proposition that at the time of the killing the appellant was suffering from an abnormality of mind, and the Court concluded that had expert evidence on coercive control been available at the original trial, the jury may have reached a different conclusion on diminished responsibility. The Challen appeal marked the first time coercive and controlling behaviour contributed to a Court of Appeal decision to overturn a murder conviction, and a high-profile witness at Challen’s retrial was forensic social worker Evan Stark, who popularized the term “coercive control.” In September 2019, the Crown accepted a plea of guilty to manslaughter by reason of diminished responsibility, and Challen was sentenced to 9 years and 4 months imprisonment, resulting in her immediate release.
The Shifting Legislative Landscape
The role of expert testimony on coercive control is closely linked to how jurisdictions define domestic abuse in statute. Controlling or coercive behaviour is a crime in England and Wales under section 76 of the Serious Crime Act (2015). This offence can be tried summarily or on indictment and carries a maximum penalty of five years’ imprisonment.
In the United States, as of the date of publication, legislation remains fragmented. As of April 2026, U.S. states with enacted coercive control legislation include Arizona, California, Colorado, Connecticut, Hawaii, Louisiana, Maine, Massachusetts, New Jersey, Vermont, and Washington. Hawaii is the only state to have criminalized coercive control; all other state laws address it in civil frameworks, primarily protective orders and child custody. Bills are pending in New York, Maryland, South Carolina, and West Virginia, among others. In South Carolina, for example, Bill 702 was introduced in the Senate on January 13, 2026, and as of publication was currently residing in the Senate.
Where statutes do not explicitly define coercive control, expert witnesses often serve as the primary mechanism for bringing the concept before the court, making the admissibility and scope of their testimony a decisive factor in whether the pattern of abuse is recognized at all.
Why This Matters
The stakes of expert testimony in coercive control cases extend beyond individual proceedings. Research cited by DomesticShelters.org indicates that offenders who exercise control over their partner’s daily activities are more than five times more likely to kill them than other domestic abusers, and in a remarkable 20 percent of domestic homicides, the murder was the first act of physical violence, though these were almost always preceded by coercive and controlling behavior. When courts lack access to expert testimony on domestic abuse that can contextualize non-physical patterns of control, these risk indicators may go unrecognized.
Evan Stark, whose 2007 book provided a foundational framework for the concept, has argued that the domestic violence revolution has stalled, tracing this failure to the paradox that a singular focus on violence masks a more devastating reality in which men use a form of subjugation that more closely resembles kidnapping or indentured servitude than assault. Legal scholars have examined what this paradigm shift might mean for the law, noting that coercive control can help redefine both criminal offenses involving domestic violence and defenses available to women who kill their abusers.
Enduring Questions
Several unresolved tensions shape the ongoing debate. First, the coercive control model asks factfinders to assess cumulative patterns rather than discrete incidents, a task for which expert witness testimony on coercive control may be essential but also raises concerns about the boundaries between expert education and advocacy. As legal scholarship has observed, to effectively present a defense involving domestic abuse, the jury must understand the kinds of coercive, manipulating, and violent tactics that a batterer employs and their impact on a victim, and expert testimony aids the jury in that assessment. Without such evidence, jurors cannot accurately assess the reasonableness of the victim’s decisions. Second, the degree to which admissibility standards such as Daubert apply to social science testimony on coercive control remains an evolving area of law. Third, the uneven adoption of coercive control legislation across jurisdictions means that the availability and relevance of expert testimony on domestic abuse varies significantly depending on where a case is heard.
Readers seeking further information may consult the Crown Prosecution Service guidance on controlling or coercive behaviour, the National Domestic Violence Hotline, or the DomesticShelters.org legal resources library.
Sources
- Crown Prosecution Service, “Controlling or Coercive Behaviour in an Intimate or Family Relationship,” CPS.gov.uk
- Serious Crime Act 2015, Section 76, legislation.gov.uk
- Columbia Law Review, “Experts as Final Arbiters: State Law and Problematic Expert Testimony on Domestic Violence in Child Custody Cases,” 2016
- Lisa Aronson Fontes, “Expert Witnesses in Domestic Violence and Coercive Control,” Psychology Today, August 2021
- DomesticShelters.org, “How an Expert Witness Can Help Your Court Case: Part 1,” July 2024
- The Global Coercive Control Legislation Index, NarcissisticAbuseRehab.com, updated April 2026
- South Carolina General Assembly, Bill 702, 126th Session, 2025-2026
Disclaimer
Coercive control law moves fast. Jurisdictions are actively criminalizing it, amending definitions, and changing the scope of litigation. This article is current as of its date of publication and may not reflect subsequent changes. It is provided for general educational purposes and is not legal advice.