Since the Minneapolis Domestic Violence Experiment (MDVE) was launched in 1981, US police have completed at least 14 randomized controlled trials of policing domestic violence. Repeated proposals to replicate any of those US tests in the UK, however, have been rejected by a succession of governments, both national and local. The need for more experiments in more countries on policing domestic abuse grows greater as the evidence from the US trials gets more worrisome. While the initial US results were encouraging (Sherman and Berk 1984), or at least equivocal (Maxwell et al. 2001), longer-term evidence now suggests that for at least one population (urban African-American women victims), the policy of mandatory arrest may cause a 100% increase in premature death from all causes among victims whose abusers are arrested (Sherman and Harris 2015).
Despite resistance to rigorous testing of police responses to domestic violence, the UK has been fertile ground for the first of evidence-based policing’s three “T”s (targeting, testing, and tracking). In a series of articles in the Cambridge Journal of Evidence-Based Policing, major insights about targeting the distribution of harm from domestic abuse are developed in Volume 1 of the Journal. These studies were stimulated in part by Chief Constable Sara Thornton’s (2011) Cambridge Master’s thesis showing that a prior history of suicide attempts was the most powerful predictor of an offender going on to commit, or attempt, domestic homicide. Since most completed or attempted domestic homicides occur in dyads (unique victim-offender relationships) with no prior police contact concerning domestic abuse, it is of great practical value to be able to identify a potential marker from other kinds of police records (including prior arrests of offenders unrelated to domestic violence) as well as records of other agencies.
Other Cambridge “pracademic” (practitioner-academic) studies of targeting differential harm from domestic abuse have replicated or supported Thornton’s evidence of the predictive value of an offender’s prior suicide attempts, or suicide ideation or self-harm. Button (2016), Chalkley (2015), and Bridger (2015) all provide new UK evidence on forecasting homicide with prior suicide attempts, rather than using a responding constable’s subjective responses to an untested checklist of questions about Domestic Abuse, Stalking and Harassment (DASH).
Further empirical evidence on segmenting case risk for targeting police resources was produced in response to the Master’s thesis of Matthew Bland, Chief Analyst of Norfolk and Suffolk Police. Bland and Ariel (2015) analysed 36,000 police records over 6 years in Suffolk to examine long-term distributions of prevalence, frequency, severity, and escalation of domestic abuse. Their analysis compiled the cases across every unique dyad meeting the broad definition of “domestic” used in UK police practice (including parent-child, wife-husband, brother-sister, boyfriend-girlfriend, and same-sex couples). In a stunning falsification of the “escalation” hypothesis, Bland’s evidence showed that 76% of dyads ever reported to the police had no repeat contact of any kind in police records. Among the 25% with one or more repeat contacts, there was some evidence of increasing frequency. But there was no statistically significant pattern of escalation in seriousness of subsequent incidents, using the Cambridge Crime Harm Index (Sherman et al. 2016) as the metric of seriousness. Bland also showed that the 75% with no repeat contact yielded only half of the total crime harm, but less than 4% of all cases yielded 80% of the total Crime Harm Index (CHI) tally.
Bland’s UK analysis was followed by Deputy Commissioner Jeanette Kerr’s analysis of 61,796 cases of intimate partner violence (IPV) cases in Northern Territory, Australia, which used a standard 4-year follow-up of all cases (Kerr et al. CJEBP 2017). While she did not find any evidence of escalation in either frequency or seriousness in the white population, she found clear evidence of escalation in one subset of the Aboriginal population.
What none of these targeting studies have shown is any support for the DASH risk assessment tool used widely by police across England and Wales. In the Thames Valley analysis, for example (Thornton 2011), none of the offenders charged with domestic homicide or attempted homicide who had been previously assessed with DASH had been identified as “high-risk”. Nonetheless, the DASH assessment tool has maintained a powerful hold on police policy and practice in the UK, especially in the face of proposed innovations that might deviate from a maximum sanctioning strategy.
The importance of targeting analyses comes from the major resource questions surrounding domestic abuse, which often receives more police responses than any other category of emergency calls to police. The challenge is compounded by the vast “haystack” of low-harm, no repeat domestic callouts relative to the very few “needles” of injury or death. Quite apart from the many other demands for police resources for threats besides domestic abuse, there is an important question of how best to protect victims of domestic abuse by reducing the overall harm level from that crime category. Should police invest equal resources in every domestic call they receive? Or should they somehow concentrate on the cases that pose the greatest risk of serious harm? If a police agency decides to concentrate on those with the greatest risk of greatest harm, what policy or practice can be used to reduce the total harm from domestic abuse?
The most common answer is a policy of mandatory arrest whenever police have forensic evidence sufficient to justify an arrest. This policy may provide either general deterrence of domestic abuse (for which there is no evidence) or an escalation in homicide against abuse victims (for which evidence has been identified by Iyengar 2010). Evidence on the effects of arrests on those arrested is more certain: in the US experiments, individual effects of arrest are very heterogeneous, with unemployed offenders increasing their domestic violence after arrests in three US experiments, while employed offenders were deterred by arrest (Sherman 1992).
Yet, even with a policy of mandatory arrest, most arrestees in the Southampton area of Hampshire were released shortly after arrest for lack of “prosecutability” to a likely conviction. The decision to take no further action (“NFA”) was reported in 55% of 2244 domestic abuse arrests in Southampton in 2012–2013, with only 33% charged and 22% convicted (Rowland 2013). Few might be happy with mandatory arrest as the primary response to domestic abuse knowing that most offenders are released without even an admonition within a few hours. Given the huge investment in mandatory arrest for these cases, the most incremental change may be to offer a low-cost follow-up to arrest that could help reduce total harm from IPV. We frame the question that way of only because the nature of abuse in a sexual relationship may have fundamentally different dynamics from those in other kinds of domestic relationships.
In the spirit of trying to get better results from the investment in domestic abuse arrests, Hampshire police began a journey 8 years ago with no roadmap or knowable timetable. Where they arrived was the first completed randomized controlled trial of a domestic violence policing strategy in the history of the UK (Neyroud 2017; see also Matheson et al. 2015).