Introduction
Although historically viewed as a private family matter, Intimate Partner Violence (IPV) has come out of the proverbial closet in the last two decades; it is now widely accepted that IPV is a broad society problem, requiring the swift and coordinated attention of the treatment community and the criminal justice system. Estimates of physical aggression between partners vary widely, depending on the definition of violence used and the context in which it is measured:

• According to the Department of Justice, roughly 1,500 instances of homicide and manslaughter between intimate partners occur annually, with more than 1,200 of these involving women as victims.
• Nearly a quarter million emergency room visits in the U.S. each year involve a victim of intimate partner violence.
• The findings of the National Crime Victim Survey, which is a survey of the victimization experiences of a nationally representative sample of the U.S. population, indicate there are nearly one million female victims of IPV each year.
• Surveys of representative samples of couples suggest that each year, one out of every eight husbands engages in physical aggressive behavior, which include less severe instances of aggression (e.g., single episodes of pushing or slapping), against his spouse.
• Women also engage in physical aggression in their intimate relationships in proportions that are equal to or slightly higher than men; however, the consequences of male-to-female physical aggression appear to be greater on the female partners, and on children in the home.

Substance Use/Intoxication and IPV
A large percentage of these IPV episodes involve alcohol consumption by either the male partner, the female partner, or both.

• More than 20% of males and 10% of females were drinking prior to the most recent and severe act of violence.
• In the National Crime Victims Survey, more than half of the victims of IPV reported that the perpetrator had been drinking.
• Among prisoners convicted of murdering an intimate partner, 45% reported that they were drinking at the time of the incident, with an average blood alcohol concentration of three times the legal limit.
• For married or cohabiting patients entering treatment for alcoholism, the proportion reporting at least one episode of IPV in the previous year is 4-6 times higher than observed in national samples.
• Depending on the study, sample, and measurement methods, the occurrence of IPV is 6-11 times greater on days of substance use (particularly on days of drinking and on days of cocaine use) than on days when no alcohol or other drugs are consumed.
• In addition, the strong relationship between alcohol use and perpetration of IPV has been found in primary health care settings, family practice clinics, prenatal clinics, and rural health clinics.

Is the Relationship Between Substance Use and IPV Causal or Correlational?
It is now widely accepted that the occurrence of violence between intimate partners is the culmination of multiple interacting contextual, social, biological, psychological, and personality factors that exert their influence at different times, under different circumstances, acting in a probabilistic fashion. Among the various factors that have been proposed in conceptual and predictive models of IPV, substance use is among the most controversial. Although there is a general consensus that those who engage in IPV often drink or use drugs and that intoxication often accompanies violence, there is far less agreement about whether or not use of alcohol and other drugs simply covaries with partner violence, is inherently facilitative or a contributing cause of IPV, or simply an “excuse” for aggression. This debate is not merely an academic exercise; if intoxication is causally implicated in IPV, it would follow that interventions which are successful in reducing substance use could reduce or eliminate the occurrence of partner violence.

Evidence supporting a causal relationship between substance use and IPV is fairly compelling and includes the following:

• Consistency of the relationship across multiple studies;
• Strength of the relationship across multiple studies;
• The existence of a Dose-Response association;
• Theoretical Coherence of the association;
• Temporal Precedence of substance use in IPV episodes;
• Experimental Evidence supporting the association.

The weakest element in the argument for a causal link between substance use and violence has to do with Rejection of Plausible Alternative Explanations. In particular, it may be difficult, if not impossible, to reject the hypothesis that an individual, who – for various pre-existing reasons - wishes to engage in violence against their partner, may subsequently drink or use drugs to facilitate such an event. Thus, as opposed to the physiological disinhibition that is often assumed, this conceptualization assumes that individuals consciously drink alcohol or use drugs in order to be violent and that intoxication provides an excuse for the behavior. For more thorough discussion of the evidence for and against the causal connection, please click here.

Representative Articles:

Fals-Stewart, W., & Kennedy, C. (2005). Addressing intimate partner violence in substance abuse treatment. Journal of Substance Abuse Treatment, 5, 5-17.

Fals-Stewart, W., Golden, J., & Schumacher, J. (2003). Intimate partner violence and substance use: A longitudinal day-to-day examination. Addictive Behaviors, 28, 1555-1574.

Fals-Stewart, W., Kashdan, T. B., O’Farrell, T. J., & Birchler, G. R. (2002). Behavioral couples therapy for drug-abusing patients: Effects on partner violence. Journal of Substance Abuse Treatment, 22, 87-96.